He thought it his best work since Streetcar and 'the very heart of my life,' but audiences and critics have found Tennessee Williams' The Two Character Play obscure and dense.

Its premiere at the Hampstead Theatre Club in 1967 came as the great American playwright was emerging from years of self-medication and mental ill health he dubbed the "stoned age'.

A fan letter to artistic director James Roose Evans after seeing a show at Hampstead, led to the staging of the experimental thriller in which actor siblings Felice and Clare, discovering their cast members have defected, act out their own play about past trauma.

Williams' late career not only suffered from substance abuse but from the straightjacket of expectation that he would repeat his greatest hits. Sam Yates, whose past productions have successfully revived lesser known work by Eugene O'Neill, has wanted to stage it for 12 years.

"I'm drawn to plays which are not well established that will feel like new pieces," he says. "Our industry like others can be risk averse and repeat what's been successful, but there are gems to be found if you take a risk.

Ham & High: Sam Yates directs The Two Character Play at Hampstead TheatreSam Yates directs The Two Character Play at Hampstead Theatre (Image: Marc Brenner)

"Williams was delighted to have it premiere at Hampstead and it's thrilling they have got behind it a second time. It will be a marvellous surprise to see him writing in a different form. I think it's special. He knew it was special, he was writing in a different way and it confused people, he felt they don't really understand it but they will one day."

With a rich seam of dark humour, the absurdist play within a play about the confining nature of human existence has been compared to Beckett.

Ham & High: The Two Character Play, L-R Kate O’Flynn, Zubin VarlaThe Two Character Play, L-R Kate O’Flynn, Zubin Varla (Image: Photo © Marc Brenner)

"As he went through his life, the things he wanted to write about and the form needed to change. It would be absurd to write the same play at 65 as he did in his 30s. It's an existential piece, two characters deciding to live or die, trying to escape the trauma and pain of a previous childhood event by making fantasy, telling a story and hiding in art - as we all tend to do - and much like Waiting for Godot, trying to reach some sort of conclusion."

Yates doesn't deny the play is challenging, but is a believer that theatre should play to its strengths as an "asker of questions".

"Williams has written something that requires engagement, piecing together, he asks lots of questions and we have to keep up. The overall effect here is expressionistic but like the best theatre it's not so much a story as an experience."

Williams famously mined his own life in his work, and indeed Roose Evans believed The Two Character Play explored his relationship with sister Rose, who was incarcerated in a mental asylum. But Yates distinguishes between the personal and biographical.

"It is close to the marrow of his being, but not especially autobiographical, He and his sister weren't actors and their parents didn't commit murder suicide, But all his plays were incredibly personal to his view of the world and relationships. We absorb the cultural view of him as poetic and symbolic but he is very rooted in the world, these are hard people being very caustic, honest and funny with each other. He had a dark sense of humour and these are two characters in extremis."

That said he agrees there are echoes of Laura and Tom in The Glass Menagerie or Blanche Dubois from Streetcar.

"With these characters in dire straits who have a childlike, gentle innocence to them, he represents our struggle to get through. I think he was a seer. He saw below the facade, but being both over sensitive and incredibly perceptive can make the world quite a difficult place."

The Two Character Play runs July 17-August 28. https://www.hampsteadtheatre.com/