Image caption Harold Pinter pictured in the early 1960s when the sketch was written

A short sketch written by playwright Harold Pinter more than 50 years ago has been found in archives at the British Library.

The piece, which is a dialogue about umbrellas between two unnamed sunbathing gentlemen, was part of a revue at Nottingham Playhouse in 1960.

Pinter's widow Lady Antonia Fraser told The Guardian she had been "completely unaware" it existed.

The British Library acquired Pinter's papers a year before his death in 2008.

But Umbrellas was uncovered by researchers delving into the Lord Chamberlain's collection. The 10-minute piece featured in a show called You, Me and The Gatepost.

Before 1968, copies of every work intended for performance had to be submitted to the state office for licensing and were retained in its archives.

The show was given the green light without any cuts and considered to be an "excellent entertainment".

Lady Antonia called the sketch - which has been reproduced in full in The Guardian - "fun" and said that her family had been acting out the sketch, in which the two protagonists are simply called 'A' and 'B'.

UMBRELLAS BY HAROLD PINTER - OPENING LINES A: The weather's too much for me today. PAUSE B: Well, you're damn lucky you've got your umbrella A: I'm never without it, old boy. PAUSE B: I think I'd do well to follow your example. Copyright The Estate of Harold Pinter 2011

"I want to act B, which is the better part, but so far I've only managed to act A.

"We're really waiting for some really good actors to do it," she added.

Jamie Andrews, head of English and Drama at the British Library, said the sketch offered "an exciting and important opportunity for all lovers and scholars of Pinter to study a piece of writing that even the writer himself had not retained".

The piece is punctuated by a series of pauses, which are considered to be a hallmark of Pinter's work.

At the time of The Umbrella's performance, Pinter, then aged 29, was enjoying success with a West End production of his play The Caretaker.

The sketch's rediscovery coincides with the opening of the newly-rededicated Harold Pinter Theatre in London.

Actress Thandie Newton is making her West End debut in Death and The Maiden, the first production in the renamed Comedy Theatre.

Pinter, whose other stage plays include The Birthday Party and The Homecoming, was awarded the Nobel Prize for literature in 2005.