Great writers often sell their letters and first drafts to libraries, and often the buyers are wealthy American institutions. But for once, a major contemporary writer's archive has stayed in Britain.
The collection includes some of Pinter's letters
Nobel Prize winner Harold Pinter has sold a lifetime's accumulation of thousands of documents, photographs, theatre programmes, e-mails and other memorabilia to the British Library.
The collection did not come cheap. The library had to find £1.1 million, raised from a number of donors and charitable trusts, plus the National Heritage Memorial Fund.
While the library's staff get to work on cataloguing their new acquisition, it is mounting a small exhibition featuring some of the highlights of Pinter's collection.
In his Nobel Prize acceptance speech - aside from condemning the US - he explained just how his plays "come about".
"In the play that became The Homecoming I saw a man enter a stark room and ask his question of a younger man sitting on an ugly sofa reading a racing paper," he said.
"I somehow suspected that A was a father and that B was his son, but I had no proof. This was however confirmed a short time later when B (later to become Lenny) says to A (later to become Max), 'Dad, do you mind if I change the subject?' "
Pinter was dubbed an "original, disturbing and arresting talent"
The British Library exhibition supplies the corroboration.
It includes a first draft, written on a yellow foolscap pad of the kind used by lawyers, of Pinter's 1978 play Betrayal, featuring a dialogue between A and B, although in the margin half-way down the first page one of the characters suddenly acquires a possible name, Emma.
And there is a typed-up draft of The Homecoming, written in 1964, with whole sections scored out and rewritten in red biro.
The characters still have no names, though one is called F (for Father) and the other 3 (for Son 3), and every so often the text is interrupted by a lower-case "p" signifying one of Pinter's trademark pauses, pregnant with potential meaning.
Pinter started out as an actor, and the earliest item in the exhibition is a photograph, taken in 1948, of him starring in a school production of Romeo and Juliet.
He owed much to an inspirational English teacher at his Hackney grammar school, Joe Brearley, who first fired Pinter's enthusiasm for literature and the theatre.
The collection includes Pinter's press cuttings
Almost 10 years later Pinter, then appearing in weekly rep in Birmingham, was writing to Brearley with news of his first wife's pregnancy and thoughts on the plays he'd been appearing in (one was "verbose and dull. The theatre has no right to be dull...") and soliciting his opinion of Samuel Beckett's Waiting for Godot.
In 1957 he also started compiling a scrapbook of newspaper cuttings and theatre programmes, starting with his first play, a one-acter called The Room.
It was performed over two nights by students at Bristol Old Vic Theatre School, and the local critics who saw it liked it.
The provincial critics liked his next play, The Birthday Party, as well when it premiered at the Cambridge Arts Theatre and then toured to Wolverhampton and Oxford: "The most enthralling experience the Grand Theatre has given us for months," said the Wolverhampton Express.
Unhappily, the London critics disagreed when the play opened at the Lyric Theatre, Hammersmith. It was almost universally panned as obscure and baffling.
"Sorry, Mr Pinter, you're just not funny enough," read the headline on Milton Shulman's review in the Evening Standard.
Only one reviewer disagreed, Harold Hobson in the Sunday Times, who called Pinter "the most original, disturbing and arresting talent in theatrical London".
But by Sunday it was too late - the play had been taken off.
Pinter cut out all the reviews, the stinkers as well as the raves, and pasted them into his scrapbook, along with a sheet detailing the Lyric's takings, performance by performance.
The library had to raise £1.1m to buy Pinter's archives
On the first night the theatre took £140 19s 6d. By the Thursday matinee there were just three people in the audience and the takings had fallen to £2 9s.
Pinter recovered from this setback and went on to write a total of almost 50 plays and screenplays - most recently a new version of Anthony Shaffer's Sleuth - and to correspond with many of the 20th Century's greatest playwrights.
There are letters in the exhibition from Arthur Miller and Sam - that's Samuel - Beckett.
And there's a fascinating correspondence with the American playwright David Mamet, whose controversial play Oleanna, about sexual harassment, Pinter directed in London. He discovered that Mamet had changed the play's original ending.
Pinter decided he wanted to keep the original version, calling it "dramatic ice".
Back came Mamet's reply by fax from the Bel Air Hotel in Beverly Hills.
"You're right. Go ahead and rehearse the sodding thing with the ending you like - you flatterer."