Helen Mirren believes you feed a cold and starve a fever. Snuffling into a restaurant’s paper napkin, she looks at her prawn cocktail arrangement in a stainless steel goblet and slops in onto a large plate. It is a gesture that has the impulsive confidence of an actress who has managed to sustain critical enthusiasm over her performances throughout the eight years since her debut. There is nothing feverish about her reaction to acting for the first time in London’s West Est, at the Lyric Theatre: “It has no theatrical world permanently attached to it,” she says.

She comes to the commercial theatre at 28 already a star, her reputation make in the subsidised, more rarified atmosphere of the Royal Shakespeare Company. Last month, she opened in Chekhov’s “The Seagull”. Next week, she appears in “The Bed Before Yesterday”, a new farce from the 89-year-old master of the genre, Bill Travers. With Joan Plowright and others, she is among a company gathered by director Lindsay Anderson in an attempt to establish a repertorx theatre in Shaftesbury Avenue. As the American critic Brooks Atkinson once said, “the word repertory is synonymous with virtue”. It’s too early to know whether virtue will succeed, as virtue should, but Miss Mirren will be around the West End for some time.

Next year, she will star in a restaged “Teeth ‘n’ Smiles”, David Hare’s play with rock music that was a recent success at the Royal Court. In it, Maggie, a sexually ravenous, whisky swigging singer, she turned on that quality – once defined as “sluttish eroticism” – which marked her first appearance at 18 as Cleopatra. While Chekhov is her meat, farce is her poison. “It’s not the kind of acting I enjoy,” she says. “It will probably be very good for me.” In her opinion the two main subsidised groups, the RSC and the National, cannot decide whether to be star-studded and successful or poor and experimental, and are flirting with both aims. “Sometimes I feel their situation is like a virginal young bride, faced with the choice of running off with a fairground boy or marrying a safe and wealthy business man, not knowing that both are impotent”. The Anderson company will provide her with a middle ground between the two extremes.

Towards the end of her stay with the RSC, she published a letter complaining of the expensive productions there. “I still think it’s an elitist theatre, glossy, glamorous and orientated towards a special audience of pretty rich middle-classes and tourists,” she says. “It’s possible to do the classics or modern pieces in a different way. The physical form of theatre is as important as the content. But there’s no true commitment to finding new forms.”