Theatrenow met Charlotte Randle to discuss Lobby Hero, the Kenneth Lonergan play that opens at the New Ambassador's on June 26, having transferred, after a very successful run, from the Donmar Warehouse.

Have you been in many other major American plays? "I've been in two other ones, at the Crucible in Sheffield. They were Arthur Miller's The Man Who Had all the Luck and David Mamet's Sexual Perversity in Chicago.

How did you find Kenneth Lonergan's play? "To me, it was a mixture of the styles of those two other American playwrights. He has the daring of Mamet and the heart of Miller."

It's only by talking to you now that I realize you're not American. How did you perfect the accent? "Thanks! Actually, we had a very good voice coach, Jill McCullough. One of the main things she taught us was that Americans have a very different energy, which is reflected in their speech patterns. "Americans tend to be forceful and hard to interrupt. Even when they are pausing between words, it's to get the energy up to push forward, whereas the British are much more reticent, and actively withdraw rather than push forward. This means the British are easier to interrupt, for example."

Well, the voice coach clearly did her job "She did, but it took us some time, and I was very worried: there have been a number of Americans over here recently, and I didn't want the critics to concentrate on our accents rather than our acting.

"Embarrassingly, the first time we met Kenneth Lonergan, the author, was at the second read-through when our accents were all over the shop, but instead of throwing up his hands, he was very supportive."

So he's easy to work with? "He's ideal! He's modest, but funny with it. When someone asked him what it was like being the only playwright other than Shakespeare to have two shows running in the West End [the other being This Is Our Youth, which was then playing at the Garrick] he said, 'Like a God!'"

How did rehearsals go? "They were fun, but they were also hard work — they were the most detailed rehearsals I've ever been in. Every line was gone over and pegged down."

What sort of research did you do for your role as a New York cop? "We had a sort of video link with a serving American policeman, who works in New York, and we were able to ask him lots of questions, which was very helpful."

In England we expect foreign police to look relatively glamorous, but the costume you have in Lobby hero isn't exactly flattering. "No, it isn't! There's a lot of it, what with the belt and all its attachments, and it gets very hot onstage while wearing it. The second half of an evening show, if I've also done a matinee that day, is always a bit of a struggle."

Where did you get the uniforms from? "They're the genuine article . . . and one of my pieces of clothing has a little label saying property of the New York Police Department — and that there's a fine of $10,000 for impersonating a New York police officer!

"The guns are only replicas, but even so there's a lot of regulations around them — if we aren't wearing them, we have to hand them over to the stage management team who have to lock them up, straight away."

You had great audience reaction as well as critical praise at the Donmar. "Yes, it was a fantastic feeling, which is one reason I'm looking forward to opening at the New Ambassador's so much. On a couple of occasions during the run at the Donmar, when I wasn't onstage I'd sneak into the Deputy Stage Manager's box and look at the audience, and they were always on the edge of their seats, absolutely gripped by the play.

"And I have to say it's as exciting to be playing it as to be watching. We have a great company, and I'm glad — especially for the play's sake — that we weren't a star vehicle. I really enjoyed watching Gwyneth Paltrow in Proof, for example, but couldn't ever quite ignore the feeling that 'this is amazing, there's Gwyneth Paltrow, only a few feet away, isn't she great?' — and that inevitably detracts a bit from fully concentrating on the play, which is what I hope people will do with Lobby Hero. The play's the star!"

—By Paul Webb Theatrenow