The late author of such emotionally charged classics as A Streetcar Named Desire and Cat On A Hot Tin Roof, who died in 1983, is thought to have written the piece when he was 26, six years before making his name with The Glass Menagerie.
Not About Nightingales was never produced, and does not appear in any of the author's collected works. It was brought to light by Vanessa Redgrave, who read a reference to it in a biography, persuaded the Williams estate to release the manuscript and then approached National Theatre artistic director Trevor Nunn to stage it in a co-production with her own company.
Nunn's staging opened last night in the National's small studio theatre, the Cottesloe.
Set in a men's prison, the play partly concerns homosexual relationships - the probable reason why American publishers and theatre managements were wary.
Trevor Nunn, who directed last night's world premiere, said he had found the work "harrowing." It has, he said, "elements of the style which you would associate with Tennessee Williams, but is not really like a Tennessee Williams play. It is about a young prisoner who has a poetic sense of himself and what he wants to achieve".
The play, which emerges as an impassioned plea for justice and humanity, was sparked off by a newspaper report of a prison riot in the Thirties in which four convicts were brutally murdered.
Nunn has recruited an Anglo-American cast in which Irish actor Finbar Lynch stars as the hero, Canary Jim, opposite American Sherri Parker Lee and Corin Redgrave, Vanessa's brother, as the prison warden.
Vanessa Redgrave came across a reference to the play in a new biography about the young Tennessee Williams. She became intrigued and went to New York to urge Williams's long time friend, Maria St Juste, who managed his estate, to release the manuscript.
Maria St Juste, who has since died, had never released the play because she felt that if Williams had not released it in his lifetime he must have had his reasons.
However, Ms Redgrave and she had been friends for some time and she agreed to release it to her. The annotated typescript was found among the late playwright's papers, and Ms Redgrave secured the rights for its performance.
The one misfortune for her was that the main female part is a 19-year- old secretary, which she is too old to play. The one middle-aged woman in the play appears only for a brief scene. Nevertheless, she was keen to play that role, until Trevor Nunn told her it would be inappropriate for her to take such a small role.