There is something I'm quite worked up about at the moment. After eight years away, I'm back in the West End, and I'm seeing first-hand what everybody has been complaining about in the business. The straight play is an endangered species. The last time I was in the Vaudeville Theatre was in Uncle Vanya, with Michael Gambon, in 1988.

A year or two later, I was in Australia about to get into a Jacuzzi, and there were two gentlemen already in it. I was hesitating whether to join them because they looked a little thuggish, to be honest. Then one of them said: “Hang on, love, didn't I see you in Uncle Vanya?”

It's true that London has something very special to offer; it is the theatre capital of the entire world. But the variety on offer in the West End is being completely eroded. The reason for that is marketing and the ways that these enormous musicals are promoted; televising the casting of musicals is having a great impact on straight theatre, because we just can't use those sorts of gimmicks to sell tickets. The length of runs is also problematic. A straight play such as The Deep Blue Sea has only three to six months to generate a word-of-mouth hit.

So I was talking to a friend about what to do about it, and we came up with an idea. We decided to give the audience questionnaires, asking them to comment on what they've just seen.

Nica Burns, our producer, was very keen to try it out, she came up with the questions, and we've been leaving them on the seats of the Vaudeville. There are six in all, asking such things as: “This play has been called a ‘modern masterpiece', one critic called it ‘dated'. What do you think?”; “On a scale of 1-10, how would you rate this production?”; and “How would you describe it to a friend?”

I haven't read the responses - I don't think it's that wise for actors to do so during a run - but I know that audiences have been responding in droves. Some are taking them home and posting them back to the theatre.

This is still a germ of an idea, evolving from seed, but Nica and other members of the Society of London Theatres (SOLT) are so, so interested by it. It absolutely isn't an attempt to topple the critical establishment. Our critics provide some of the most brilliant analysis and honest personal opinion anywhere. But it's an attempt to give more power to the word-of-mouth response of audiences.

And it would be fantastic if everyone knew there was a website where the responses were collected. It would let you know immediately, when you were looking to find out what's on, what other audiences thought about it. It would have to be run by an independent body such as SOLT, and be very fair, authentic and trustworthy rather than just producers trying to sell their own shows. And at the same time, it could provide genuine ticket-office numbers for the shows, to tackle the huge problem of criminal ticket sellers in London overcharging people or lying about what's available purely on the basis of what they have to sell.

It's a very small idea, I know, and a very new one. But my hope is that the questionnaires might fight back a bit against the massive marketing manoeuvres of the West End musicals, to give good, straight plays in the West End more of a chance by harnessing the power of the word of mouth. Whether it works or not in the long term, I don't know. Right now, we're just running with it. We'll have to see where it takes us.

The Deep Blue Sea is at the Vaudeville Theatre, WC2 (www.nimaxtheatres.com; 0844 4124663)

As told to Lucy Powell

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