QUIZ / There are more questions than answers: Nick Lezard watches members of the RSC take on the National in their annual contest of theatrical knowledge

On the set of Carousel at the National's Lyttelton Theatre, two teams of actors are preparing to fight over a crutch. Not just any old crutch, mind. This is Antony Sher's black crutch from his production of Richard III - a big draw in contemporary theatrical iconography, the ultimate prop-up prop.

The fight is actually the ninth annual Theatre Quiz. Four players from the National Theatre and four from the Royal Shakespeare Company are set to face off and answer theatrical questions from Ned Sherrin. This is a needle match. The NT, having recently won three quizzes in a row, got to keep the previous prize, Ralph Richardson's walking stick. But the RSC have won the last two contests. If they win tonight's battle, they get to keep Sher's crutch for good, instead of just having it float around the dressing-rooms for a year.

I ask if I can go behind the scenes and hear Ned Sherrin's pre-quiz briefing. I can't. Apparently the panel members are very nervous. Nervous? They're actors, aren't they? 'They're appearing as themselves,' explains the Press Officer. 'That's probably why they're so nerve-racked.'

The strangest thing is that the Lyttelton Theatre is packed, and it's only six o'clock. There is standing room only. I scout the cast list for clues which might give me an insight into this huge turn-out. Who is the big attraction? The RSC team: Desmond Barrit, Ian Judge (capt), Estelle Kohler and Robert Stephens. The NT team: Robin Bailey, Nicholas Hytner (capt), Vicky Licorish and Betty Marsden. Chaired by Ned Sherrin, guest scorer Jane Horrocks. Signed copies of Ned Sherrin's Theatrical Anecdotes (hardback and paperback) are available at the Lyttelton bookshop.

Sherrin and Horrocks - she was the stroppy anorexic in Life is Sweet and the dizzy secretary in Absolutely Fabulous - I know. But the others? They ring bells, but only faintly. A lifetime's non-theatre-going has taken its toll. I am ashamed of my own ignorance, and they haven't even been asked any questions yet.

Ned Sherrin bounds into the central chair. Unlike the actors who are so anxious about appearing as themselves, Sherrin doesn't have a personality he need be worried about exposing. Hardly has he sat down before he puts everyone at ease with an I-had-a- funny-cab-driver-on-the-way-here story (he was mistaken for Clive James). He speaks with breakneck authority, as if in a perpetual state of only having time for just one more question.

'For no points,' he asks Robin Bailey (who, I discover later, has acted in everything from When We Are Married to Sorry, I'm a Stranger Here Myself) 'what is your connection with the pop group Simply Red?' Bailey, the event's elder statesman, looks blank. As does everyone else. It turns out that he was born in Hucknall, which also happens to be the surname of the band's singer. The audience groans. The proper questions begin.

'Where are the theatres named after the following actors?' Sherrin asks. 'Laurence Olivier.' The Olivier Theatre is about 14 seconds' walk away from the Lyttelton, so everyone knows this one. As it turns out, it is the only question all evening which I am able to answer. Other theatres (you can try this at home): Thomas Moore, Sybil Thorndike, Yvonne Arnaud, Michael Redgrave, Flora Robson, David Garrick (actually, I think I got that one too), Ethel Barrymore and Helen Hayes? Full marks if you got them all right. The teams didn't. Jane Horrocks read the scores out at the end of each round in a funny voice, which, I realised, is her normal voice.

The questions get harder. Scratchy old 1950s recordings of Marlowe Society productions of A Midsummer Night's Dream (or 'the Dream', as we pros call it) are played, and actors identified. Or not. There is a round of quotation-spotting, including Howard Barker ('I send my plays to the National for rejection, so that I know I can still see clearly'), Madonna (?), and John Cleese (who said 'Fuck off, you ignorant caterer'; I forget to whom*, because I dropped my pen when Ned Sherrin said the f-word). I am surprised how many of the questions escape the teams. Perhaps it is because they have spent too much time acting and not enough time going to the theatre. Nicholas Hytner, the director of, among other things, Carousel, seems to be answering every question for the NT.

It's the final round. The teams have to say which West End musicals, produced in 1992, contained the following songs: 'I Took My Heart to a Party'? No one knows. The National Theatre team guesses Which Witch. No. It is Radio Times. 'Unworthy of Your Love'? Which Witch, tries the RSC. No, Assassins. 'Who Do You Love, I Hope'? The NT makes a stab at, er, Which Witch. 'I thought,' says Sherrin, a dash of acid creeping into his voice, 'that there were some of you who thought they know about musicals.' The song came from that arcane cabaret Annie Get Your Gun, by the obscure songwriter Irving Berlin. 'I Do Miracles?' By this stage no one wants to say Which Witch again. But they don't get it. It is from Kiss of the Spiderwoman. 'Shadows of the Deep'? 'For Christ's sake,' says Nicholas Hytner, 'this has got to be from Which Witch.' No, Moby Dick. Sherrin then reads out a song title which begins 'Six hundred and sixty- five billion', runs through all the remaining digits, and ends with the words 'Little Devils'. The RSC is nonplussed. 'I'll have to hand it over to the other team,' says Sherrin, a phrase so much part of him now that I half hope he has it inscribed upon his tombstone. 'Which Witch?' ventures Hytner, 'Correct]' says Sherrin. Hurrah] The National Theatre has won Antony Sher's crutch. The audience goes wild.

Everyone waves and kisses each other. Grown men sob uncontrollably. Bouquets rain down on the stage and I run out for a drink.

*John Cleese's insult was faxed to Gerry Robinson, who was responsible for replacing David Plowright as chairman of Granada Television.