Class conscious - Andrew Stephen braves a night at the theatre

A night at the theatre is the culture world's equivalent of having to do a five-mile run

There was a slight reservation in my gratitude as I received from my wife the gift of a ticket to see The History Boys by Alan Bennett at the National Theatre. I revere Bennett; I've read most of his stuff, or seen it on film or video or heard it on tape. But I have tended to avoid experiencing him (or any other good playwright) in his natural state: that is, on stage.

My brother-in-law, who used to be a theatre critic, once mounted a "campaign for shorter plays". I'm very much in favour of shorter plays, or no plays at all. I admire the set for the first three minutes (there is no such thing as a bad theatre set, as far as I'm concerned), and then I find myself somehow sharing the exhaustion of the actors as they try to project their voices and yet retain a naturalistic tone. To me, plays look like rehearsals of films, and I am baffled by - and slightly disbelieving of - all those middle-class north Londoners who say that the theatre is the thing they love best about the capital.

I admit that a trip to the National Theatre is special, however. It is the focus of intelligent London, and going there is like moving to the centre of the encampment to warm your hands by the crackling fire. But why are the seats so small and uncomfortable? I regard sitting on one of those for three hours as a physical challenge equivalent to running approximately five miles.

Then there's proximity to powdery, middle-aged ladies swathed in strange cloaks, and the heat (it's always too hot at the National), combined with the cloying, headache-making scent of other people's sucked peppermints. There's all that business of settling down: the arranging of coats on rickety knees, the passing along of the little bottle of mineral water; it's like the moment before taking off in an aeroplane. Except that take-off is always exciting, whereas you could say the same of about only one in 50 plays.

My seat for The History Boys was in the stalls at the Lyttelton, number D6, and last Tuesday I set off towards it, thinking of the last time I'd been to the National. It was about two years ago, to see The Front Page by Ben Hecht and Charles MacArthur. The set was outstanding, but I left after the interval even so. As Harold Pinter once told a friend of mine, "sometimes it's more important to have a drink in the bar".

As I entered the National Theatre, I was, as usual, stunned by the sheer middle classness of the place. The music being played by the foyer band was like the conversation going on all around me: excessively polite. In the theatre bookshop, I noticed, you can actually buy a sweatshirt commemorating 21 years of Theatre de Complicite. I looked at one of these, imagining all the places in which it would never be seen: betting shops, dog tracks, massage parlours, pubs in which food is not served, Torremolinos, Blackpool.

En route to my seat, I asked the ticket checker when the play would finish. "Ten-forty," he said. Eight o'clock to 10.40. It's a long time. You could get to Darlington on the train in that time. I took my seat feeling fraught. If anyone could pull this off, it was Bennett, but still . . .

Suddenly a man leaned across me holding a ticket. "D6," he said. "You're in my seat." I waved my own ticket dismissively towards him. "I've definitely got D6," I said. "Yes," said the man, "but your ticket is for tomorrow."

He was clearly braced for an argument but I tell you, I sprang up, and I bounded out of that seat. "Here," I said, "it's yours."

I went back the next day when, curiously, the National Theatre seemed to be full of exactly the same people. As for the play? The History Boys is terrific, and now I don't have to go to the theatre for another year.