North Downs Line
AClass 165 unit approachingDorking West with the hills of theNorth Downs behind
Overview
Status	Operational
Owner	Network Rail
Locale	Berkshire,Hampshire,Surrey
Termini	Reading Redhill
Service
Type	Heavy rail
System	National Rail
Operator(s)	Great Western Railway South Western Railway Southern
Rolling stock	Class 165,Class 166,Class 450,Class 458,Class 377
History
Opened	1849
Technical
Line length	45 mi 40 ch (73.2 km)
Track gauge	1,435 mm (4 ft 8+1⁄2 in)standard gauge
Electrification	Third rail, 750 V DC (Reading–Wokingham; Aldershot South Junction–Guildford; Reigate–Redhill)
Operating speed	70 mph (110 km/h) (maximum)
Route map Show static map Show zoomable map Legend Great Western Main Line Reading Reading Southern River Kennet Earley River Loddon Winnersh Triangle Winnersh M4 motorway Wokingham B3349 road Waterloo–Reading line Crowthorne Sandhurst Blackwater M3 motorway Farnborough North South West Main Line North Camp LC North Camp Alton line Basingstoke Canal Aldershot Farnham Junction │Ash Tongham │ Ash LC Ash Green Halt Ash Junction closed December 1960 Wanborough Portsmouth Direct line New Guildford line Guildford Chalk Tunnel St Catherine's (Sand) Tunnel Portsmouth Direct line River Wey Shalford A248 road Chilworth LC Chilworth Brook LC Burrows Lane LC River Tillingbourne Gomshall Westcott Range Halt Dorking West Dorking Deepdene Sutton and Mole Valley lines Dorking link closed 1946 River Mole Brockham LC Betchworth Quarry Betchworth B2032 road Buckland LC A217 road Reigate Redhill Brighton Main Line Redhill–Tonbridge line Show line diagram

TheNorth Downs Line is a railway line inSouth East England. It runs for 45 miles 40 chains (73.2 km) fromReading inBerkshire toRedhill inSurrey. It is named after theNorth Downs, a range ofchalk hills that runs parallel to the eastern part of the route. The name was introduced in 1989 byNetwork SouthEast, the then operator. The North Downs Line serves the settlements in theBlackwater Valley as well as the towns ofGuildford,Dorking andReigate. It acts as an orbital route around the south-west of London and has direct connections to theGreat Western Main Line at Reading, theWaterloo–Reading line atWokingham, theAlton line atAsh, thePortsmouth Direct line atGuildford and theBrighton Main Line at Redhill.

Three differentoperators run passenger services on the North Downs Line.Great Western Railway runs services along the entire length of the line from Reading to Redhill, the majority of which continue along the Brighton Main Line toGatwick Airport.Southern trains betweenReigate andLondon Victoria use a 1 mi 67 ch (3.0 km) section west of Redhill.South Western Railway services between the capital and Reading use the line west of Wokingham and the same company operates between Guildford andAsh en route toAldershot.

The majority of the North Downs Line was constructed by the independent Reading, Reigate and Guildford Railway company (RG&RR), although the section between Guildford and Ash Junction was built by theLondon and South Western Railway. The line opened in 1849 and services were run from the outset by theSouth Eastern Railway, which took over the RG&RR in 1852. Three sections of the line were electrified by theSouthern Railway in the 1930s although around 29 route miles (47 km) remain unelectrified. In the early 21st century, infrastructure works to increase the capacity of the line were undertaken, including the provision of new platforms at Reading and Redhill.

The North Downs Line is a 45-mile-40-chain (73.2 km) railway line inSouth East England. It linksReading railway station on theGreat Western Main Line inBerkshire toRedhill on theBrighton Main Line inSurrey.^[1][2] It serves the settlements in theBlackwater Valley on the borders ofHampshire, Surrey and Berkshire, as well as the Surrey towns ofGuildford,Dorking andReigate. It acts as an orbital route bypassing the south-west of London and has direct connections to theWaterloo–Reading line atWokingham, theAlton line atAsh and thePortsmouth Direct line atGuildford.^[1][3] The 2015 "Surrey Rail Strategy" noted that 56% of passengers on the route connect to services on other railway lines and that a quarter of journeys either start or end at Reading. Around 13% of passengers travel to or fromGatwick Airport.^[4]

The name "North Downs Line" was first used in 1989 byNetwork SouthEast, the then operator of the line.^[5][6] Between Redhill and Ash, the line runs roughly parallel with theNorth Downs, a range ofchalk hills that runs fromFarnham to theWhite Cliffs of Dover. Between Ash and Reading, the line crosses the sands, gravels and clays of theLondon Basin.^[7] The steepest gradients, 1 in 96, and the summit of the line are nearGomshall, where the route crosses thewatershed between theRivers Mole andWey in Surrey.^[8][9] The distances along the line between Redhill (22 miles 40 chains) and Shalford Junction (41 mi 60 ch), and between Ash Junction (48 mi 34 ch) and Reading (68 mi 68 ch) are measured fromCharing Cross station in London.^[10]

The North Downs Line is double track for the entirety of its 45 mi 40 ch (73.2 km) length and has a maximum operational line speed of 70 mph (110 km/h) for passenger trains.^[11][12] Three sections of the line, Redhill–Reigate, Guildford–Aldershot South Junction and Wokingham–Reading, are electrified using the 750VDC third-rail system.^[13][14][15] Two sections, Reigate–Shalford Junction and Aldershot South Junction–Wokingham, together totalling 29 route miles (47 km), are unelectrified.^[1][11] The line has a W6loading gauge, and overnight engineering possessions of up to4+1⁄2 hours are available.^[16] In 2006,Network Rail classified the North Downs Line as "congested", but, following the construction of new infrastructure, this status was revoked in 2023.^[17]

The Reading to Guildford section of the North Downs Line is 25 mi 41 ch (41.1 km) in length and has 13 stations in total. Reading and Guildford stations are managed by Network Rail^[19][20] and have 15 and 7 operational platforms respectively.^[21][22] The other 11 stations have two platforms each.^[23][24]Earley,Winnersh Triangle,Winnersh, Wokingham, Ash andWanborough stations are managed bySouth Western Railway (SWR).Crowthorne,Sandhurst,Blackwater,Farnborough North andNorth Camp stations are managed byGreat Western Railway (GWR).^[18] The passenger train services that use this section of the North Downs Line are:

• Reading to Redhill andGatwick Airport, operated by GWR usingClass 165 andClass 166 units^[1][18]
• Reading toLondon Waterloo, operated by SWR usingClass 458 andClass 455 units^[25][26][27]
• Farnham andAldershot to Guildford, operated by SWR usingClass 450 units^[28][29]

West of Wokingham Junction and east of Aldershot South Junction, this part of the line is electrified using the 750 V DC third-rail system, leaving an 11 mi 71 ch (19.1 km) unelectrified central section.^[14][23][24] Most services on the North Downs Line use platforms 4, 5 and 6 at Reading station, but access to other platforms is possible. The Reading station area is controlled from Thames Valleyrail operating centre, the line from Earley to North Camp is controlled by Basingstoke rail operating centre, and the section from North Camp is controlled by Guildford signal box. The majority of this section has a line speed of 70 mph (110 km/h) with the exception of the approaches to Reading, Wokingham and Guildford stations, and a 40 mph (64 km/h) restriction at Ash Junction where the line curves sharply.^[23][24] The steepest gradient, to the west of Guildford, is 1 in 100.^[30]

TheWaterloo–Reading line diverges from this part of the North Downs Line at Wokingham Junction, and a spur to theAlton line joins at Aldershot South Junction.^[31] In addition, the line passes beneath theSouth Western Main Line atFarnborough, but there is no longer a junction between the two.^[32] This section passes over two navigable waterways, theRiver Kennet and theBasingstoke Canal,^[33][34] as well as the unnavigableRiver Loddon and its tributary, theBlackwater.^[33]

Between Guildford and Shalford Junction, GWR trains use the Portsmouth Direct line to travel between the two parts of the North Downs Line. The route passes through two tunnels, Guildford Chalk Tunnel and St Catherine's Tunnel.^[33] Reversible working is available on the down line on this section of track.^[16]

The Shalford Junction to Redhill section of the North Downs Line is 19 mi 79 ch (32.2 km) long and has eight stations in total.^[49][50] Reigate and Redhill stations are managed bySouthern, but the remaining six stations (Shalford,Chilworth, Gomshall,Dorking West,Dorking Deepdene andBetchworth) are managed by GWR.^[18] Redhill has four platforms, but the other seven stations have two each.^[49][50] The passenger train services that use this section of the North Downs Line are:

• Reading to Redhill and Gatwick Airport, operated by GWR^[18][d]
• Reigate toLondon Victoria via Redhill, operated by Southern^[52]

Much of this part of the North Downs Line runs immediately to the south of the North Downs escarpment,^[7] although the route deviates to the south between Chilworth and Gomshall to avoidAlbury Park.^[8] Only the 1 mi 67 ch (3.0 km) section between Reigate and Redhill is electrified.^[53][54] Between Shalford Junction and Gomshall, the line is controlled from Guildford signal box and the majority of the route to the east is controlled by Reigate signal box.^[49][50] Redhill railway station and its approaches are controlled by Three Bridges rail operations centre.^[55] The maximum speed on this part of the North Downs Line is 70 mph (110 km/h).^[49][50]

The route crosses theMole Valley Line immediately to the east of Dorking Deepdene, but there is no longer a junction between the two.^[56] The navigable River Wey is crossed at Shalford via a steeltruss bridge, which replaced the original wooden bridge in 1902.^[57] The North Downs Line crosses the River Mole on a five-arch, brick viaduct, built when the line was constructed in the late 1840s.^[58] TheA24 dual carriageway at Dorking is crossed on a steel bridge, installed in 1964.^[59]

TheReading, Guildford and Reigate Railway company (RG&RR) was formed in August 1845.^[69][70] It was led initially by Frederick Mangles, a banker from Guildford,^[71] and most of the board members were businessmen from London and Surrey.^[72] The company's stated objective was to build a line linking the three towns in its name to "secure through traffic passing between the West, North and Midlands and the Channel Ports avoiding the congestion of London and thus saving time, distance and expense."^[72]

The engineer,Francis Giles, was commissioned to survey the line. His route, presented to the board in January 1846, had an estimated cost of £710,000 (equivalent to £86.85 million in 2023) and was to be double track throughout. It would run from the Great Western Main Line at Reading to the Brighton Main Line at Reigate Junction (later Redhill). Between Dorking and Gomshall, Giles's route required the use of the proposedLondon & Portsmouth Direct Atmospheric Railway.^[71] The approaches to Guildford would use part of theLondon and South Western Railway (LSWR) lines toGodalming andAlton.^[73][f]

Negotiations with other railway companies began at the start of 1846. By mid-January, the RG&RR had bought out the rival Reading and Reigate Company, promoted byDavid Mocatta, which had proposed a line with similar aims. That March, it agreed terms to run over the LSWR tracks from Shalford Junction to Guildford. In the same month, theSouth Eastern Railway (SER), which had wanted to build its own short branch from Reigate Junction to Dorking, offered to operate the line.^[73][74] A bill was prepared for Parliament and the RG&RR was authorised on 16 July 1846, the same day that the LSWR'sline from Guildford to Alton was approved.^[75] The act gave the RG&RR the powers to construct the section of the line from Dorking to Gomshall, if it was not built in time by the London & Portsmouth Direct Atmospheric Railway Company.^[73]

Francis Giles died in March 1847 and his position as surveyor and engineer was taken, on a temporary basis, byRobert Stephenson.^[34][76] Stephenson began to make changes to Giles's scheme, primarily to reduce costs. Around £3000 was to be saved by simplifying the link to the South Western Main Line at Farnborough, eliminating the north–west curve, leaving only the north–east curve to be built. At Reading, Giles had proposed running alongside the Great Western Main Line on a widened embankment, but Stephenson argued that the RG&RR should build a separate station (later known asReading Southern) instead of sharing theGreat Western Railway (GWR) facilities. Minor alterations were also made to the route in the Gomshall,Albury and Ash areas. A deviations bill was submitted to Parliament and was givenroyal assent on 22 July 1847.^[32]

A formal ceremony to mark the start of construction took place near Betchworth on 20 August 1847.^[77][g] Contracts were awarded to George Wythes and William Jackson for the construction of the Reigate Junction-Dorking and Farnborough-Reading sections. In mid-1848, the plans for the London & Portsmouth Direct Atmospheric Railway were abandoned^[78] and the contract to build the Dorking-Shalford Junction section of the RG&RR was awarded to Charles Henfrey that May.^[34][72] The SER was responsible for constructing the stations on the eastern half of the line, for which it was paid £25,000.^[79]

Peter Barlow was appointed engineer in late 1847, although the exact date is uncertain. He disagreed strongly with Stephenson's alterations to the station arrangement at Reading but was unable to persuade the RG&RR board to reinstate Giles's original scheme. Barlow made some minor alterations to reduce costs, including reducing the span of the bridge over theBasingstoke Canal from 40 ft (12 m) to 24 ft (7.3 m). He also suggested building the Dorking to Farnborough section as single track, but the board decided to continue with Giles's plans for a fully double-tracked railway.^[34] Following the conclusion of negotiations with the LSWR, a bill authorising the curve linking the RG&RR to the South West Main Line at Farnborough was granted royal assent on 26 June 1849.^[79]

Two sections of the line, from Farnborough to Reading and from Reigate Junction to Dorking, opened on 4 July 1849.^[80][81][h] Locomotives and rolling stock were delivered to the western section via the single-track link to the South West Main Line.^[83] From the outset, the line was worked by the SER. The initial timetable was four trains in each direction per day between Farnborough and Reading. There were seven trains from Dorking to London on weekdays and one fewer in the opposite direction.^[84][i]

The sections from Dorking to Shalford and from Guildford to Farnborough opened in August 1849. The collapse of St Catherine's Tunnel delayed the completion of the LSWR-constructed Shalford Junction to Guildford section, which finally opened on 15 October 1849.^[80][87][j] The initial daily full-line timetable included six trains from London to Reading, with five in the opposite direction, supplemented with an early morning departure from Guildford to the capital and an equivalent mid-evening return.^[88]

During the construction of the line, the RG&RR was unsure how best to serve the villages ofShere and Gomshall. When passenger services on the section between Dorking and Shalford began in August 1849, two temporary stations opened – one for each village. The Shere Heath station was closed the following year, and a permanent station was built at Gomshall to replace the temporary platforms there.^[83] In 1851, a platform was opened at the point where the line crosses the Dorking-London road. Initially called Box Hill and now known as Dorking Deepdene, the new station was intended to cater to passengers from theLeatherhead area.^[83]

The first freight trains began running on the line in September 1850.^[89] Goods sheds opened at Gomshall and Betchworth the following year, and a shed was provided at Ash from 1856. The yard at Dorking, equipped with an 8-ton crane and cattle pens, served both the town and theDenbies estate.^[89]

In October 1851, the SER applied to Parliament to take over the RG&RR.^[90] The purchase took effect in March 1852, although the authorising act was not given royal assent until 17 June 1852.^[83][91] Over the first few years of SER ownership, the financial performance of the line was poor. In 1855, the company stated that the line was losing £15,377 per annum (equivalent to £1.8 million in 2023), but the following year, theRailway Times estimated that the annual loss was around £30,000.^[90] Through trains from the GWR at Reading were introduced on 1 July 1863 with a dailyBirkenhead toDover return working, but disappointing passenger numbers resulted in the service being withdrawn in October 1868.^[85][92] In January 1869, there were five daily return services between Charing Cross and Reading, ten between Dorking and the capital, and one from Guildford.^[93] Passenger numbers from Dorking fell after the opening of the Leatherhead to Horsham line in 1867.^[85]

In the mid-1850s,Aldershot Military Town was established for theBritish Army in north-east Hampshire.^[94][95] In 1858, the SER opened North Camp station to serve the new camps.^[96] A goods yard was constructed at the station in 1859-60.^[97]

Several connections between the North Downs Line and other lines were created in the second half of the 19th century. The first was a 300 m (330 yd) single-track link running into the GWR station at Reading, which opened on 30 August 1855.^[98] The Staines, Wokingham and Woking Junction Railway (SW&WR), which had been granted running powers over the Wokingham-Reading section in 1853, opened its line from Ascot on 9 July 1856.^[96][98] A second link at Reading, which passed under the Great Western Main Line and which was owned by the GWR and SW&WR, was opened to goods services on 1 December 1858 and to passenger trains on 17 January the following year.^[99] At Dorking, a single-track west-to-south spur joining the Leatherhead-Horsham line, was opened on 1 May 1867 but closed around the end of the century.^[56] The fourth link, a tight curve to theAlton line allowing SER trains from Ash to run intoAldershot station, was completed in 1879.^[82][31]

●

The uncompleted triangular junction with thePortsmouth Direct line in 1871: The red circle indicates the position ofShalford station.

The construction of the railway line from Godalming toHavant was completed in late 1858, although the first passenger services did not start running until January the following year.^[100] Since the line had been built on a speculative basis by the independent Portsmouth Railway (PR) company, it was unclear whether the LSWR would allow its trains to run over its line via Guildford and Woking to reach London. In July 1854, the PR gained authorisation to extend its line northwards from Godalming to Shalford, where it could join the North Downs Line.^[101] New embankments and a woodentrestle bridge across the River Wey were constructed by the SER to create atriangular junction at Shalford, providing an alternative route to the capital. However, before the link could be completed, the LSWR decided to allow PR trains to use its line, eliminating the immediate need for the connection.^[31] It is unclear whether track was ever laid over the spur, but the SER decided not to continue its work, fearing that completion would violate its long-standing agreement with theLondon, Brighton and South Coast Railway not to compete for traffic to Portsmouth.^[102]

As a result of theRailways Act 1921, the North Downs Line became part of the Southern Railway in 1923.^[103] Three parts of the line were electrified in the 1930s using the third-rail system. The 1.9 mi (3.1 km) section between Redhill and Reigate was electrified under the Brighton Main Line electrification programme. Electric trains began running in public service on 17 July 1932, with trains to and from Reigate splitting and joining at Redhill with trains to and fromThree Bridges.^[13][53] The electrification of the Wokingham–Reading and Guildford–Ash sections was completed on 1 January 1939.^[14][15][k] One further development to take place in the 1930s was the withdrawal of the passenger service on the former LSWR line between Ash Junction andFarnham viaTongham on 4 July 1937. Freight services on this route continued until final closure in 1961.^[105]

During the Second World War, the North Downs Line was fortified with additional earthworks, tank traps andpillboxes.^[106] A nine-roadmarshalling yard was built at Shalford and the link to the Dorking–Horsham line at Dorking was reinstated.^[56][l] The North Downs Line played a major role in the transport oftroops evacuated from Dunkirk in May and June 1940.^[103][106]

The firstBeeching report, published in 1963, recommended shutting all stations between Shalford and Betchworth inclusive.^{[107][108][109]} Instead of the proposed partial closure, steam-hauled passenger trains were replaced bydiesel multiple units in January 1965, although steam-hauled freight continued until the end of the decade.^[110][111] The final through services between London and Reading via Redhill (one train in each direction per day) were withdrawn at the same time.^[112] On 4 January that year,Class 206 units, nicknamed Tadpoles and officially designated 3R, began operating an hourly stopping service betweenTonbridge and Reading, calling at all stations except Winnersh and Earley.^[113] The second Beeching report, which was published in February 1965, recommended that the whole of the North Downs Line should be developed as a trunk route for freight services.^[114]

Reading Southern station closed on 6 September 1965 and all North Downs Line services were diverted to platform 4a at the main Reading station thereafter. Platform 4b at Reading opened in May 1975.^[115] In November 1967, full-time staff were removed from all stations on the line, with the exception of Redhill, Guildford and Reading. The change was made possible with the introduction of conductor-guards, with the ability to sell tickets, on all trains.^[111] An express service between Gatwick Airport and Reading began in May 1980, calling at North Camp, Guildford and Redhill. These trains began stopping at Dorking Deepdene in May 1986.^[116][117]

From 1982, the North Downs Line came under the control of Network SouthEast, one of the five business sectors ofBritish Rail.^[118][5][m] In 1989, groups of lines in the sector were given names and identities; the Reading–Tonbridge and Reading–Gatwick airport services were branded the "North Downs Line" and the crest of the former Tonbridge Urban District Council was applied to the trains.^[5][6] In 1993, the Class 165 and 166 units were introduced. The reaction to the new trains was positive and, over the following 12 months, a 46% increase in passenger numbers was recorded for North Camp.^[117] Tonbridge remained the easternmost terminus for the North Downs Line services until the electrification of theRedhill–Tonbridge line in 1994, when the stopping services were cut back to Redhill.^[120][121]

As the result of theprivatisation of British Rail, the North Downs Line was included in theThames Trains franchise, won by theGo-Ahead Group in 1996.^[122][123] The franchise was awarded toFirstGroup in 2003^[124] and trains were branded "First Great Western Link" for the next two years.^[125] In 2006, the former Thames Trains operations became part of theGreater Western franchise, won by FirstGroup.^[125][126]

In the 2010s, additional platforms were opened at Reading,^[127] Redhill^[128] and Gatwick Airport stations,^[129][130] to increase capacity for trains using the North Downs Line and other passenger services. A major project to renew the signals in the Wokingham area and to transfer control of the north-western part of the line to the Basingstoke rail operations centre was completed in February 2024.^[131][132]

Several foot crossings were replaced by bridges in the early 21st century, including at Gomshall station in 2016,^[133] Shere Heath in 2021^[134] and Farnborough North station in 2025.^[135] Chester Bridge, which carries the A323 over the railway, opened in February 2025, allowing the level crossing to the south of Ash station to be closed to vehicles.^[136][137]

The main services on the North Downs Line are provided by GWR usingClass 165 andClass 166 Networker Turbo diesel multiple units. There is a half-hourly service between Reading and Gatwick Airport via Guildford, with alternate services running semi-fast either side of Guildford.^{[18][138][139]} At Redhill, the Gatwick Airport services reverse to head south along the Brighton Main Line. A total of seven diesel multiple units is required to run the GWR Reading–Gatwick Airport service.^[1][n]

Services on the North Downs Line are provided by South Western Railway between Reading and Wokingham (trains to/fromLondon Waterloo, operated byClass 458 andClass 455 units),^{[25][26][140]} and between Ash and Guildford (trains to/from Aldershot and Farnham operated byClass 450 units).^[28][140]Class 701 units are expected to start operating services between Waterloo and Reading in June 2025.^[141][142]

Southern operates frequent services using four-car electric multiple units between Reigate andLondon Victoria. These trains use the North Downs Line between Reigate and Redhill, where they join the Brighton Main Line.^[1]

The earliest locomotives to be used on the North Downs Line are thought to have been SER2-4-0 engines, designed byJames Cudworth.^[143] ANasmyth and Gaskell0-6-0 and aHick 2-4-0 are known to have worked the line in the mid-1850s.^[112] E class 2-4-0 locomotives were introduced in the early 1860s and hauled passenger services until the end of the 19th century.James Stirling, who was appointedlocomotive superintendent at the SER in 1878, introducedF class4-4-0 engines to the line in 1897.^[143] From 1902,Q class0-4-4Ttank engines were used and are known to have worked the Ash-Aldershot shuttle services.^[144]

Traffic increased during the First World War, with additional trains serving the army camps at Aldershot. GWR3300 class "Bulldogs" and3252 class "Dukes" were deployed to the line, supplemented by 15Great Northern Railway 2-4-0 locomotives.^[144][145] In 1924,MaunsellN class steam engines began hauling passenger trains, andP Class 0-6-0 tank engines took over the Ash-Aldershot shuttle at around the same time. In the 1930s, the majority of services were worked byF1 andD class 4-4-0s, andH class 0-4-4Ts.^[144][146] In 1938, ex-GWR2-6-0 and4-6-0 engines moved to the North Downs Line and continued to haul trains until the 1960s.^[146]

Traffic increased again during the Second World War. Between 27 May and 4 June 1940, troops evacuated from Dunkirk were transported via the line and civilian services were suspended to allow these trains to run.^[146][147] In the same year a new cross-country service betweenNewcastle andAshford, Kent, primarily for military personnel, was introduced on the line. It ran until the end of 1944, when the southern terminus was changed toSouthampton Docks.^[146]

In the 1950s, the majority of passenger trains were hauled by Maunsell N andU class locomotives, supplemented towards the end of the decade byStandard Class 4 tender andtank engines. From 1959 onwards, electrification schemes in Kent allowedLSWR N15 class "King Arthurs" andSR V class "Schools" steam engines to be transferred to the line.^[147]Class 33diesel-electric locomotives began hauling trains in 1962.^[148] The final, scheduled, steam-hauled passenger service on the North Downs Line departed Reading Southern for Guildford on the evening of 3 January 1965,^[149] although a few steam-hauled freight services continued until the end of steam operation on the Southern Region in July 1967.^[110]

A new timetable was introduced on 4 January 1965, with3R (Class 206) diesel-electric multiple units operating an hourly, all-stations service between Reading and Tonbridge. The new trains consisted of two 6S (Class 201) coaches from theHastings Line coupled to an adapted2-EPBdriving trailer coach. As a result of the visible difference in width between the narrow Hastings Line stock and the standard-width trailer, the units were nicknamedTadpoles.^[150][151] The Class 33 diesel locomotives, introduced to the line in 1962, continued to haul peak hour services until May 1977.^[148][152]

Three-carClass 119 units were introduced to the North Downs Line in April 1979 enabling the withdrawal of the Tadpoles in May 1981.^[109] The express service from Reading to Gatwick Airport was launched on 12 May 1980. The Class 119 units were especially modified for this service, and the buffet counter in the centre coach was removed to create extra luggage space.^[153] Initially the service called at North Camp, Guildford and Redhill, but it began stopping at Dorking Deepdene in May 1986.^[117] Three-carClass 101 units were later used on the route as well.^[154] The Class 119 and 101 units were replaced by Class 165 and 166 units in 1993.^[117]

Class 456 units were introduced to the North Downs Line on 23 March 2014, when they began operating between Ascot and Guildford via Aldershot. They were withdrawn from passenger service by SWR on 15 January 2022.^[155][156] In 2018, GWR announced that it would leaseClass 769 hybrid multiple units for use on the North Downs Line and on other services in the Thames Valley.^[157] In 2022, the company decided not to pursue plans to introduce the Class 769 fleet and stated that all units were to be returned to the lessor.^[158]

The first goods trains began running on the North Downs Line in September 1850 and facilities for handling freight were provided at most stations. Goods sheds opened at Gomshall and Betchworth the following year, and a shed was provided at Ash from 1856.^[89] The yard at Dorking, equipped with an 8-ton crane and cattle pens, served both the town and theDenbies estate.^[89] The permanent goods yard at Reading Southern opened on 1 December 1858, replacing a temporary facility to the east that had opened with the line in 1849.^[159] The yard was used for goods services in February 1970.^[160] Most of the station yards on the line closed in the 1960s.^[161][162]

There were four major narrow-gauge railway systems linked to the line. The Chilworth gunpowder and cordite works, active until the end of the First World War, had an800 mm (2 ft 7+1⁄2 in) railway.^[163] At Dorking West station, there was a British Timber Works narrow gauge railway, active between the 1910s and 1930s. Brockham Limeworks and Brickworks, to the east of Dorking, was connected to the North Downs Line by a standard-gauge siding but also had a small2 ft (610 mm) system.^[164] Betchworth quarry and limeworks, which operated between 1865 and 1963, had an extensive system with four different track gauges.^[165][166]

Thetravelling post office train fromDover toManchester Piccadilly via Tonbridge, Redhill, Guildford and Reading was routed along the line from May 1988^[152] until 1996, when a new road and rail postal hub opened at Willesden.^[85] The Network Rail 2008 Strategic Business Plan recommended an enhancement project to enable freight traffic from theChannel Tunnel to use the line.^[167] In 2023, there were no regular scheduled freight services on the North Downs Line.^[168]

Three sections of the North Downs Line were electrified by the Southern Railway in the 1930s,^[13][14][15] but around 29 mi (47 km) remains unelectrified.^[1][11] There have been several proposals to either extend the electrified sections or to completely electrify the remainder. A study for Surrey County Council, published in two parts in 1995 and 1996, recommended that the Dorking–Reigate section be electrified and a north–east link from the Mole Valley Line be built, to enable a loop service to operate viaEpsom, Redhill andEast Croydon.^[169][o]

The "Surrey Rail Strategy", published in 2015, noted that infill electrification of the remaining unelectrified sections using the DC third-rail system would reduce the journey time between Reading and Gatwick Airport by2+1⁄2 minutes for fast services and by 7 minutes for stopping trains. Overhead electrification of the line would reduce the journey time by 5 minutes for fast services and by 11 minutes for stopping trains.^[170] The following year,Surrey County Council suggested that electrification of the full length of the North Downs Line would create around 8,000 jobs and would stimulate £1.9 billion of economic growth, based on research by fourlocal enterprise partnerships.^[171][172]

The "North Downs Line Traction Decarbonisation Strategy", published byNetwork Rail in 2024, evaluated the costs and benefits of completely electrifying the route. It noted that third-rail infill offered poor value for money and proposed that battery-powered electric trains should be procured when the Class 165 and 166 units are withdrawn. Whilst introducing a third train per hour between Reading and Redhill would allow stops to be removed from Reading–Gatwick services, it would deliver only a marginal improvement in the financial performance of the line.^[1]

The "Blackwater Valley Rail Survey", published in 1991, suggested replacing the station at Farnborough North with an interchange station where the South West Main Line crosses the North Downs Line. This option was dismissed in the 1995/6 Surrey County Council reports as it was thought that the stopping train frequencies on the two lines would be too low for suitable connections.^[169] The 1995/6 reports also proposed a new station at Park Barn to serve theRoyal Surrey County Hospital and theUniversity of Surrey. A local newspaper report in 2019, suggested that the new station, in north-west Guildford, could open in the mid-2020s.^[169][173] The 1995/6 Surrey County Council reports also suggested that the line could form the core of a rail link betweenHeathrow and Gatwick Airports.^[174]

• 19 June 1853: An SER passenger train from Reading to Reigate ran into the back of a Godalming-bound goods train in one of the tunnels south of Guildford.^[175]
• 12 September 1855: Alight engine, which had departed from Reading, was misrouted into the path of a train from Charing Cross via Guildford and collided with it head on. Three passengers and thedriver of the light engine were killed.^[112][176] One further passenger later died of their injuries.^[177]
• 17 January 1867: An LSWR passenger train from Alton ran into the back of an SER train from Reading about 300 yd (270 m) north-west of Guildford station. There were no fatalities.^[178]
• 18 January 1868: An SER train for Redhill derailed shortly after leaving Reigate, due to alandslip. The locomotive overturned, the first carriage was destroyed and the second carriage was slewed across the tracks. There were no fatalities.^[179]
• 8 September 1882: George White, a shunter employed by the SER, was struck and killed at Reigate by a non-stopping express train to London. He had been loading a horse into a horsebox attached to a Reading-bound train that had stopped at the station.^[180]
• 29 February 1892: Henry Wicks, a guard employed by the SER, was killed on the line between Chilworth and Gomshall. A coupling between two trucks broke and the rear portion, in which he was working, rolled backwards downhill at speed. He was thrown out of theguard's van and onto the embankment.^[181] Abox hedgetopiary, known as Jessie's Seat, has been cut in the shape of a pheasant as a memorial to Wicks.^[182]
• 9 November 1901: Afireman was run over and killed in thick fog by a non-stopping train at Blackwater, while attempting to extinguish a burningsleeper.^[183]
• 20 February 1904: A locomotive hauling a train carrying around 150 members of theRoyal Northumberland Fusiliers, bound for service in Mauritius, derailed at Gomshall station. There were no fatalities, but three soldiers, the driver and fireman were severely injured. The accident occurred while the train was travelling at around 35 mph (56 km/h) and is thought to have been caused by a track defect.^[181][184]
• 11 April 1944: Two goods trains, one of which consisted of tankers of aviation fuel en route to airfields in Kent, collided at Shalford. The resulting fire damaged the steel road bridge over the railway.^[185]

There are three Grade IIlisted structures on the North Downs Line.

Name	Location	Type	Completed[p]	Date listed	Coordinates	Image	Ref.
Level Crossing cottage	Buckland, Surrey	cottage	1848	18 August 1996	51°15′02″N0°15′17″W / 51.2505°N 0.2546°W /51.2505; -0.2546		[186]
Footbridge immediately south of Wokingham Station	Wokingham, Berkshire	footbridge	late 19th century	16 June 1996	51°24′39″N0°50′33″W / 51.4109°N 0.8425°W /51.4109; -0.8425		[187]
Railway overbridge at NGR SU 7770 7109, Arbor Lane	Winnersh, Berkshire	rail bridge over road	1848	28 April 1987	51°26′00″N0°53′02″W / 51.4333°N 0.8838°W /51.4333; -0.8838		[188]

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