Josie Lawrence: Whose career is it anyway?

Her breathtaking improvisations on Whose Line is it Anyway? made her a household name, but Josie Lawrence is equally at home in serious theatre. On the eve of her appearance as a criminal psychologist in Frozen at the National, she talks to Robert Hanks

The image of Josie Lawrence that is lodged in my head, and I suppose in lots of other people's, is Josie the Improv Queen on Whose Line is it Anyway? – bright-eyed and bushy-tailed, flying by the seat of her pants as she cheerily belted out impromptu lyrics with atrocious rhymes at top speed: a mercurial, spontaneous talent. But that was a while ago; these days, her career revolves around careful preparation and repetition.

Last year, she stepped into Elaine Paige's shoes for a stint as Mrs Anna in The King and I at the Palladium – eight shows a week for nine solid months. Now she is appearing in Bryony Lavery's three-hander Frozen at the National Theatre – a transfer of the premiere production, which was staged at Birmingham Rep in 1998. You can't get much less spontaneous than that.

The reasons for this long-delayed transfer aren't entirely clear. Lawrence says that there was talk of moving to the National back then, when the play had received some rapturous reviews, but no stage was available. Four years on, out of the blue, the call came saying, How about now? She says she didn't even have to think about it: so now she is reunited with the original cast, Tom Georgeson and Anita Dobson, and the director, Bill Alexander.

It is a sombre play. Georgeson plays a serial killer who specialises in young girls; Dobson is the mother of one of his victims. Lawrence plays Dr Agnetha Gudmundsdottir, a criminal psychologist from New York, visiting Britain to pursue the question "Serial Killing – a Forgivable Act?" The play includes extended monologues as well as dialogue; and Lawrence's part includes an academic lecture.

For Lawrence, this second bite at the cherry is a very happy experience. One reason, she is evidently consumed with awe and affection for her fellow actors, and for Bill Alexander – he also directed her in a 1996 production of The Alchemist. But another reason is that, despite her background in improvisation, she evidently gets a kick out of doing a part over and over again. As she tells it, this is not a rejection of her roots in improvisation so much as an extension of it: "When I did Mrs Anna, people said 'How could you do something for that long?' ... But I have always been someone who enjoys going on stage and finding new things out every night. I don't want to sound too actory, but I like keeping things fresh."

She recalls the pleasure of constant rediscovery during a run of The Cherry Orchard at the RSC, in which she played the servant Dunyasha: "The very last night," she says, "I found out something I'd never found out about her." On enquiry, this turns out to be a very trivial matter: she had to drop some teacups, breaking a saucer, then clear up the mess with her hands; she kept cutting her fingers on the shards. What she realised on that last night was that she could scoop the shards into her apron – this was not only kinder on her hands, but also looked rather good.

From that, you might judge that she is one of those actors who finds the character through external details, rather than using the details to express a preconceived idea of the character – the very opposite of Method. You might also think that she is not inclined to intellectualise the processes of acting. When I ask her what it was like to pick up Frozen four years after she left off, she says "Well, that was very interesting," but follows up with generalities about "finding stuff we'd missed the first time round, just little details that you could tweak because you were aware of the shape of the play", and seems a little uncomfortable with the idea of going into more detail. But she is also simply grateful to have been chosen for a serious part, since she does not see herself as obvious casting.

"I know that Whose Line Is It Anyway? made me a kind of household name for a while, and that was great, and I'm completely beholden to it – I think for a while I used to try and back off away from it, 'I do more than that, you know'." These days, she's quite happy to be recognised because of the programme; but, she says, "There have been occasions when I haven't been able to audition, even, for a part, because the powers that be on that particular project have said 'She's a comic'."

If that's so, it's very shortsighted. My abiding memory of her on stage comes from Gale Edwards' production of The Taming of the Shrew for the RSC in 1996, in which Lawrence played Katherine. Her final speech of perfect wifely submission, more than problematic for modern audiences, is sometimes treated ironically, with a nod and a wink to show some complicity between Kate and Petruchio. In this case, it was taken deadly straight, as if Kate's spirit had been utterly broken, like a confession at a Moscow show-trial. No sane man, you realised, could want a marriage founded on this sort of inequality. It wasn't an altogether convincing approach to the text, but I thought Lawrence did it really well.

I'm surprised when she talks about the difficulties of finding the right work – I'd assumed she was enough of a celebrity to make up her own mind about what she did. But, she says, "I'm not the kind of person that just gets sent scripts. I audition for parts and stuff." She is hardly ever unemployed, indeed she hasn't taken a holiday for six years (apart from one skiing trip, which she hated because she was no good); but she doesn't get to pick and choose between parts.

And while theatre has offered her some diverse parts, on television, which is where most of us see her, she has been getting typecast as a comic gorgon – in the sitcom A Many-Splintered Thing, starring Alan Davies, she was the hero's girlfriend's predatory lesbian landlady; while in Kay Mellor's dieting comedy Fat Friends, which has just finished filming a second series, she plays a slimming guru with a decidedly overweight ego. She says she'd like to play somebody really straightforwardly evil; and she also mentions that future plans include more Shakespeare, but won't go any further at this juncture. Bearing that "Shrew" in mind, I quite fancy seeing her have a go at Goneril or Regan. Maybe even Lady Macbeth.

But these little moans aside, she says she's terribly pleased with the way her career is going. The King and I has been a highlight – she got to do the whole gamut of emotions, from "Whistle a Happy Tune" to the king's death, and she had a lovely letter from the Rodgers and Hammerstein Association in New York congratulating her on her performance. "And you got to wear a really beautiful dress. And you got to dance with a very good-looking king on the revolve at the Palladium. I mean, how good is that?"

'Frozen' opens at the National Theatre, London SE1 (020-7452 3000) on 3 July