One of the most important postwar literary archives will remain in Britain after the British Library yesterday announced it had acquired the letters, manuscripts, scrapbooks, photographs, programmes and emails of Harold Pinter.

The library has paid £1.1m for more than 150 boxes of the dramatist's personal archive, which includes more than 12,000 letters between Pinter and virtually all the leading theatrical figures of the last 50 years, from Samuel Beckett to Joseph Losey to Arthur Miller to David Mamet.

The move bucks a recent trend of literary archives heading abroad, particularly to the US and institutions such as the University of Texas in Austin, which owns the archives of David Hare and Tom Stoppard. Jamie Andrews, head of modern literary manuscripts at the British Library, said the news was "thrilling".

He added: "This is a wonderful collection that sheds new light on each stage of Harold Pinter's unparalleled career over the past 50 years.

"There are issues around some archives going to American institutions and we have been working very hard to fly the flag and encourage British writers to leave their archives in this country."

Given Pinter's strongly expressed views on American foreign policy and other aspects of the US - Hollywood is a "shithouse", he told Time Out magazine last month - it would have been a shock if his archive had followed his compatriots' across the Atlantic. The archive is a treasure trove. Among the piles of letters is one from Noel Coward, who professes himself a fan. "You cheerfully break every rule of the theatre that I have been brought up to believe in except the cardinal one of never boring for a split second," he writes.

There is also a series of letters between Pinter and his friend Samuel Beckett, as well as correspondence with a new generation of writers including the late Sarah Kane, whom Pinter always supported.

The laborious process of cataloguing has begun on the acquisition, which was secured in part by a £216,000 grant from the National Heritage Memorial Fund, which gave money to save the archive of a living artist for the first time. Visitors will be able to get an early peek when 30 or 40 highlights from the archive will be displayed at the British Library next month.

The Hackney-born dramatist received the Nobel prize for literature in 2005.

This year there have been well-received revivals of his plays in London, including The Dumb Waiter, The Hothouse, and Betrayal.

At the cinema the Pinter-scripted adaptation of the film Sleuth is showing, starring Michael Caine and Jude Law, while in the West End a double bill of early plays, The Lover and The Collection, opens at the ComedyTheatre next month.

Pinter said yesterday: "I am delighted that the British Library has purchased my archive. I am very pleased indeed that it will stay in this country."

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