TheGreat Britain Historical GIS (orGBHGIS) is aspatially enabled database that documents and visualises the changinghuman geography of theBritish Isles,[1] although is primarily focussed on thesubdivisions of the United Kingdom mainly over the 200 years since the firstcensus in 1801. The project is currently based at theUniversity of Portsmouth, and is the provider of the websiteA Vision of Britain through Time.
NB: A "GIS" is ageographic information system, which combinesmap information withstatistical data to produce a visual picture of the iterations or popularity of a particular set of statistics, overlaid on a map of the geographic area of interest.
The first version of the GB Historical GIS was developed atQueen Mary, University of London between 1994 and 1999, although it was originally conceived simply as a mapping extension to the existing Labour Markets Database (LMDB). The system included digital boundaries forregistration districts andpoor law unions (c.1840 to 1911),local government districts (1911 to 1974), andparishes (1870s to 1974). These boundaries were held not as polygons but as line segments (arcs), usingArcGIS software. Dates of creation and abolition were held for each line segment (or "arc") and custom software was developed to assemble line segments into polygons, creating conventional boundary maps for particular dates. Meanwhile, the Labour Markets Database evolved into the Great Britain Historical Database (GBHDB), which stored a large collection of historical statistics from the census, vital registration and records of poverty and economic distress. These were held in thousands of columns within hundreds of separate tables, within anOracle database. This system is described in detail inGregory and Southall (1998), and inGregory and Southall (2002).
The second version of the GB Historical GIS was developed at theUniversity of Portsmouth from 2000 onwards. The work was mainly funded by the UKNational Lottery, so the results had to be useful to a far wider audience than mosthistorical GIS projects.

This is a truespatial database in which all content is held in Oracle, although GIS software is used to edit content. It is designed to overcome the limitations of the original system:
This new version of the GB Historical GIS also included several other kinds of content:
All of this new content is held in the same Oracle database and linked to the polygons and statistics inherited from the original GBHGIS.
A GIS consisting entirely of administrative boundaries can create maps but these are hard to relate to the real world. The project has therefore constructed a second GIS consisting entirely of scanned images of historical maps, supporting an on-line map library.
Three complete sets of one inch to one mile maps of Great Britain have been scanned and geo-referenced, each accompanied by less detailed maps from the same period:
This collection of historical maps is not held in the main Oracle system. They are instead managed using open sourceMapServer software. However, they are mainly accessed via MapServer's implementation of theOpen Geospatial Consortium'sWeb Map Service standard. This is how they are used by the GB Historical GIS project's Vision of Britain system, but they are also available for use as base maps by other web sites.
Britain has had an unusually large number of changes to its local government geography, and the current districts date back only to 1996, to 1974 or, in London, to 1965. As census reporting has always been based on local government units, it is hard to study how any particular area has changed in the long term. One of the main reasons for building the GB Historical GIS was to enable demographic and social statistics to be 're-districted from various historical units to modern districts. This is done using a vector overlay methodology, using parish-level counts of total population to weight the reallocation of district-level data.
This methodology has been used to replicate the most important statistics from theKey Statistics release from the 2001 census for many earlier dates, including total population from 1801, occupational structure for selected censuses from 1841 onwards, and age and gender structure for every census from 1851 onwards.
Components of the GB Historical GIS are available for download by academic researchers from theUK Data Archive and fromEDINA's UKBorders system. However, the main way most people can access the system is via the Vision of Britain web site, developed by the GB Historical GIS project with their lottery funding.
The site is designed mainly as a resource for studying local history but also includes extensive mapping facilities. It includes home pages both for "places", i.e. towns and villages, and for the individual administrative units based on places. Administrative unit pages provide access to census statistics for the unit, to boundary maps and to formal information on official names and status, relationships with other units and boundary changes. All these web pages are generated by software from the data held in the underlying GB Historical GIS. Many Wikipedia pages refer to Vision of Britain.
Vision of Britain is an unusual web site as it isdatabase-driven, but uses the ontologies in the underlying system to create clickable links between pages: most pages the site can create can be reached without filling out a search form, or clicking on an image map, and this makes the site's content generally accessible to search engines. One result is that Google searches for historical information for particular places in Britain are very likely to return links to Vision of Britain. For the most reliable results, search in Google for "place county history"; for example, "Portsmouth Hampshire History".
For a detailed guide to using the Vision of Britain system for research into local history, seeSouthall (2006).
The post-2000 GB Historical GIS makes no use of commercial GIS software, except for editing parts of the content, and implements a data model which could not be implemented using packages such as ArcGIS or MapInfo, so is it a GIS at all? It is certainly not a conventional GIS, but one answer is that any system that can create an image like the one shown below is some kind of GIS. This image fromA Vision of Britain through Time combines the boundaries of local government districts, data on unemployment from the 1931 census, and a scanned image of an Ordnance Survey ten mile-to-one inch map from the early 20th century.
A new system is being developed, partly with funding from the European Union under the QVIZ project, which will no longer be limited to Great Britain:
An enhanced web site based on this extended system was launched in 2009.[citation needed]