Only 21, but she's already the toast of the West End

At the age of 19, when most people are wondering what to do with their lives, Polly Stenham was busy writing her first play. This week, the young writer, now 21, was named most promising playwright of the year for her tale of a dysfunctional, upper-middle class family that stunned theatre critics when it made its West End debut in April.

Surrounded by such theatrical greats as Sir Ian McKellen, Dame Eileen Atkins and Patrick Stewart at the Evening Standard Theatre Awards, Stenham was presented with the award and a 25,000 cheque for her play That Face, which premiered at the Royal Court Theatre.

The play, which won a string of rave reviews, is shot through with Oedipal overtones, telling the story of a mother (played by Lindsay Duncan) addicted to alcohol and prescription drugs whose teenage children are forced to parent her. The work also features an absent financier father and scenes of Abu-Ghraib-style bullying in a girls' boarding school.

Stenham hails from a decidedly upper-middle class background, although she has insisted that the family in her play bears no relation to her own. She is the daughter of the late Unilever tycoon Anthony "Cob" Stenham, who brought up Polly and her younger sister Daisy single-handedly after splitting with their mother. He inspired his daughter's love of theatre, taking her to see plays from an early age by writers ranging from Harold Pinter to Sarah Kane.

But Stenham, who wrote That Face as part of the Royal Court's Young Writers programme, fell into the theatre almost by accident. "I wanted to write fiction really, but I couldn't find any courses and then I heard about the Royal Court," she said. Writing the play was, "a lot of fun".

She is now "in the murky depths" of writing a second. "It would be completely possible that I now write four or five terrible plays," she said. "You lose your innocence a bit. The first one you just write for you and the complete joy of it."

In That Face, girls at a boarding school engage in cruel "initiation rites". While Stenham was educated at Wycombe Abbey, a leading public school in Buckinghamshire, before moving to Rugby in the sixth form, she insists the scenes are "very exaggerated". "There were these rituals and traditions; the school really tried to get rid of them. It was also [based on] other schools that my friends went to."

Ola Animashawun, the head of the Young Writers programme, said: "As soon as we read the draft [of That Face] it was just cracking with excitement. It's unusual to get people writing about that class of people as highly dysfunctional.

"Allied to that, the writing is totally arresting from the word go. It's really sharp, it's acute."

Indicating a bright future for Stenham, he added: "We regard her as very much part of the set-up here."

"She's very confident. I would urge more young writers to have that belief."

Nicholas de Jongh, the Evening Standard's theatre critic, said: "The most exciting moments in the theatre... are those when you suddenly realise that you are in the presence of a major new talent. I had no doubt that this was the case during the premiere of Polly Stenham's That Face at the Royal Court Theatre Upstairs last April.

"It raised the hairs on the back of my neck and left me both shaken and stirred."

The CV

* Born: 1987

* Education: Wycombe Abbey; Rugby College; Ambassador Writer's Group; Royal Court Young Writers programme.

* Debut play: That Face, Royal Court Theatre,London, April 2007.

* Awards: 2007 Charles Wintour award for most promising playwright; 2007 best new play TMA award

* Review: "This is one of the most astonishing debuts I have seen in more than 30 years of theatre reviewing. In every respect this is a remarkable and unforgettable piece of theatre." - Charles Spencer, Daily Telegraph