The Norman Conquests took place in three different rooms on three successive nights. That was a hit, but when he produced a similar formula for The Revengers' Comedies in two nights, it flopped in the West End. "People didn't know whether they had to see them in a certain order," he recalls. "House and Garden might not work at the National Theatre, but they stand a better chance there than in the West End.

There's more flexibility." (House and Garden can be seen in either order.)Ayckbourn writes faster than any living playwright, and 99.44 per cent of the dead ones too. He does spend months beforehand working out a plot in his head. But when he started to write this, he says, he had to go really fast at it. To find out where the characters were - the house or the garden - it was important to get the plot on paper. The writing took 10 days, and that was twice as long as usual.The zeitgeist is late-Major. One clue is a reference to the Arts Minister as "some temporary, very, very minor post". The sexual frankness that devastated Major's administration is to be found in the plot too, though the lovemaking is, Ayckbourn-style, between two people who do not understand what they are saying to each other "Once you could drive a whole play on sexual taboos I've loosened out since.

I hope sex doesn't swamp everything, but it does drive the characters in one way or another," he says.The final problem of one play in two theatres with one cast is the curtain calls. Since they have to take their bow in both the Olivier and the Lyttelton, one group of actors is puffing along the yellow line while another group is receiving the applause. If the running group is late, there will be some operatic-length curtain calls Allied to a collective shortage of puff.. Lesley Manville, who played Kitty Sullivan in Topsy Turvy, Mike Leigh's recent Gilbert and Sullivan biopic, once told me that she thought the composers of the Savoy operas were the Sex Pistols of the 19th century.