Lia Williams' acting career started fast and furious and has continued in a similar vein.

She was still in drama school when she joined the company of the first West End outing of Daisy Pulls It Off and, after that, went straight into Alan Ayckbourn's production of The Revenger's Comedies for which she was named Most Promising Newcomer by the Critics' Circle and nominated for Best Comedy Performance at the 1992 Laurence Olivier Awards.

Since then, Williams' notable stage credits have included: the title role in David Mamet's Oleanna, directed by Harold Pinter at the Royal Court and in the West End; and Richard Eyre's National Theatre production of David Hare's Skylight, which transferred to the West End and Broadway and earned her both Olivier and Tony nominations for Best Actress.

More recently, she performed Pinter's double bill of Celebration and The Room at the Donmar and, last year, brought The Gate Dublin's revival of Pinter's The Homecoming to the West End, co-starring opposite Ian Holm and winning a Award Best Actress nomination.

Williams' film and television credits include The Russian Bride, Dirty Weekend, That Girl from Rio, A Shot Through the Heart, Imogen's Face, The King Is Alive and Mr Wroe's Virgins. She has also recently directed a short film, Feathers, based on a Raymond Carver story.

The actress opens this week in the world premiere of Shelagh Stephenson's Mappa Mundi at the National Theatre. Originally due to open on 24 October, the production was delayed by two weeks following the withdrawal due to illness of Williams' co-star Ian Holm, who has now been replaced by Alun Armstrong.

Date & place of birth
Born 26 November 1963 in Birkenhead.

Trained at...
The London Studio Centre.

Lives now in...
I've lived in West Hampstead for the last five years.

First big break
It was the original production of Daisy Pulls it Off in the West End - I was in the second cast as an understudy while I was still at drama school, and then I took over the role of Sybil Birlington, the little monster.

Career highlights to date
It has to be: Skylight, because I met Michael Gambon and we went on to Broadway with it; Oleanna, because it bullied a British audience into shouting matches which is a quite un-English thing to do; and Harold Pinter's latest play, Celebration, together with his first-ever play The Room, at the Almeida and which we then performed in New York - it was just fantastic to lift the roof off a New York audience with laughter.

Favourite productions you've ever worked on
Alan Ayckbourn's The Revenger's Comedies was the thing that launched me into the world of great writers and great directors, and was probably the most challenging and glorious role I've played to date. I had to play six different characters in the course of a five-hour long play. It was good to do great comedy - it is rare to find good comic writing, particularly in theatre. Also, David Hare's Skylight - to work with Richard Eyre and Michael Gambon was all one could wish for.

Favourite co-stars
Whoever I'm working with at the time.

Favourite directors
Danny Boyle, whom I did a television film called Mr Wroe's Virgins with - he's an explosive, intuitive director the likes of which I haven't come across before or since. I also loved working with Richard Eyre and Harold Pinter. Richard has exquisite sensibilities and great subtlety, and Harold is probably the closest thing to genius I've ever met.

Favourite playwrights
David Mamet, Harold Pinter and Alan Ayckbourn, who I have worked with; and Tennessee Williams, who I've not done any of yet, but am about to, next spring. I'm doing a little known but very beautiful Williams play, The Eccentricities of a Nightingale, at the Gate Theatre in Dublin.

What roles would you most like to play still?
Probably roles that haven't been written yet - I like new writing particularly. I'd love to be offered the classics, but I have no aspiration for anything specific.

What's the last thing you saw on stage that you really enjoyed?
I loved Ivanov, Katie Mitchell's production at the National - it transported me to another world meticulously and beautifully. It was played with tremendous humour, and I had no idea it was such a brilliant play and so subversive. I also loved Long Day's Journey into Night with Jessica Lange - her performance was fantastic.

What advice would you give the government to secure the future of British theatre?
I'd probably encourage more spending on innovative people, like directors, writers and producers, and not just institutions - to encourage the Peter Brooks and Joan Littlewoods of the future.

If you could swap places with one person (living or dead), who would it be?
John Pilger, because he challenges the government and corruption and the thinking of the status quo constantly.

Favourite books
The Heart Is a Lonely Hunter by Carson McCullough. I'll read anything of hers, she's a genius writer and it's a shame she died so young. I read Camus' The Outsider in one sitting, and it had an enormous impact on me. I also love Raymond Carver's writing, and his collection of short stories called Cathedral.

Favourite after-show haunts
A club that I'm a member of, the Union in Greek Street. It's quiet and unpretentious with strange lampshades, but it's a lovely place to go and the food is fantastic.

Favourite holiday destinations
I rarely plan a holiday, so I am always taken by surprise with them. But I'd say Budapest - the way the Danube winds its way through old and new Budapest is exquisite, particularly on a cold, starry night. It's a very romantic place to be.

Favourite joke
Tim McInnerny (who also appears in Mappa Mundi) told me a good joke the other day that made me laugh: Why doesn't an actor look out of his window in the morning? Because he'll have nothing to do in the afternoon.

If you hadn't become an actor, what would you have done professionally?
I'd have been a scuba diver - because it's absolute heaven under the water. I've only ever done it once, but it's so peaceful and beautiful.

Why did you want to accept your role in Mappa Mundi?
I'm playing Anna, a lawyer who is about to get married. She's fairly neurotic about this, and the play is also about her relationship with her father and her brother's relationship with his father. I was attracted to it because I'm always attracted to new writing. Shelagh Stephenson has a particularly deft style that is beautifully comic but also leaves you with a sense of something afterwards - in this case, a sense of mourning - which is unusual.

Mappa Mundi deals a lot with ancestry. Have you researched your family tree?
No, I couldn't get into it, it would take me years and I don't have the patience.

What's your favourite line from Mappa Mundi?
A line from Jack, the father character: "I started out as a particle, travelled as a wave, and I'll arrive as a particle."

What's the most notable thing that's happened during Mappa Mundi rehearsals?
Ian Holm pulling out of the production, four days before we were due to open (originally on 24 October), because he's not well and has a blood protein disorder. But Alun Armstrong brilliantly and boldy stepped in.

What are your plans for the future?
I'm doing the Tennessee Williams play in Dublin, and also Frank McGuinness has written a version of Ibsen's The Lady from the Sea for me to do. But the most exciting thing that happened to me this year was directing my first short film, and I have a plan to put into motion now to direct another full feature length film. The short film was based on a Raymond Carver short story, Feathers. My partner Guy Hibbert wrote the screenplay, and we filmed it with Jane Horrocks, Ian Hart, Brenda Blethyn and Sophie Thompson. I hope it will be a calling card for people to back further ideas.

- Lia Williams was speaking to Mark Shenton

The rescheduled season of Mappa Mundi, directed by Bill Alexander, runs at the NT Cottesloe from 7 November 2002, following previews from 2 November.