IT is the only stage play written by one of Scotland's greatest writers, but for decades it has lain disused and forgotten - until now.

Muriel Spark's sole script for the stage, Doctors of Philosophy, which had a brief run in London in the early 1960s but has been neglected since, is to be re-staged in Edinburgh this summer.

The rehearsed reading of the funny, witty, and quietly avant-garde play, with five "amazing" lead roles for female actors, is to be produced by the Edinburgh International Book Festival and the Royal Lyceum Theatre.

Muriel Spark celebrated: Year long series of celebrations to mark 100 years since writer's birth

David Greig, the playwright and director of the Lyceum, has expressed surprise that the "very, very funny" play - which he describes as mix of Wildean wit, the black comedy of Joe Orton and the influence of Italian dramatist Luigi Pirandello as well as replete with Spark's wit and intelligence - has remained unproduced for so long.

Brief excerpts of the drama, which centres around the contrasting lives of two female academics, plus a group of male characters all called Charlie, were staged at the recent celebration of Spark's work at the Usher Hall and the theatre has committed to a full performance.

At the book festival the play will have a fully rehearsed reading with a cast of actors, yet to be named, directed by Marilyn Imrie.

Greig said he was first told of the play by Professor Willy Maley of the University of Glasgow, and was curious why the play had not been performed by a professional theatre since its run at the Arts Theatre in Soho in 1962.

Greig, who hopes to launch a fully staged version in the future, said: "I really think it's a gem, an undiscovered gem.

"When I came to me, I thought: if it's not been done, there's a reason for it, but I thought I'd have a look.

"I read it and laughed out loud three or four times.

"I thought: this is really brilliant, it felt like a combination of Joe Orton, there's Pirandello, there's Wilde, there's even bits of Beckett, and overwhelming the whole thing is Spark: this detached but very cool wittiness, and five amazing female characters, each one is big, bold and funny and interesting.

"All the men are called Charlie: it's such a brilliant reversal. So why was it overlooked?"

Muriel Spark celebrated: Year long series of celebrations to mark 100 years since writer's birth

Greig said that the play's debut in 1962 may have been overshadowed by the success and fame of the Angry Young Men, a group of male British playwrights, notably John Osborne, who came to the fore in the mid-1950s.

He noted: "It opened to not-bad reviews.

"A couple of things went against it, but the primary one was that this was the moment of the Angry Young Men, you are in the wave of Look Back in Anger and 1956 and all that, and red-blooded heterosexual Englishmen writing about angry, gritty life.

"Many of those plays are brilliant, but what was being pushed out was gay life, in that [Terence] Rattigan mode, French plays, intellect and ideas and women.

"I think she [Spark] just had the wrong moment: this play is very French in terms of its ideas and intellect, its about witty repartee and middle class dialogue, it has all the things that were undervalued and underrepresented, and she was also, of course, doing great as a novelist."

Spark's life and work is being celebrated this year in the 100th anniversary since her birth, is best known as the author of 22 novels, but she also wrote several radio plays.

Nick Barley, director of the Edinburgh International Book Festival, said “Doctors of Philosophy is an astonishing piece of theatre which demonstrates Muriel Spark at the peak of her powers and the audience response in January was extraordinary.

"We were extremely keen to bring the play in its entirety to the Book Festival and we are delighted that we have been able to continue our collaboration with The Lyceum to bring a full rehearsed reading of the play to Charlotte Square Gardens in August.”

Muriel Spark celebrated: Year long series of celebrations to mark 100 years since writer's birth

Director Marilyn Imrie previously worked with the Book Festival in 2016 when she directed the theatrical adaptation of Alice Munro’s View From Castle Rock.

The rehearsed reading of Muriel Spark’s Doctors of Philosophy will take place on19 August in the Spiegeltent in Charlotte Square Gardens.