It is teatime at the Royal Garden Hotel in London. In a suite overlooking Kensington Gardens, tiny cucumber sandwiches, scones and sponge cakes, all arranged on a cakestand, along with tea in a silver teapot, are being served by an expressionless waiter to the pony-tailed founder of the Mothers of Invention. It is 1971. Most guests at this august establishment are in three-piece suits and twinsets. It is a credit to the record company that Frank Zappa got into this hotel at all.

However, the hotel was not to know that Zappa deliberately projected a counter-culture image and that the reality was an acute businessman with a wide-ranging taste in music and a conventionally homely home high above Los Angeles.

But back to teatime. The suite is tidy. There are no groupies loitering and Frank's partner, Gail, is overseeing the tea pouring. Frank is entranced by their son, Dweezil, aged two, who is dismantling the bidet. As yet, water hasn't flooded the bathroom floor, and in all probability if it did Frank wouldn't discourage his son. "Isn't that great?" he marvels. "Can you believe he can do that at his age?" The waiter beats a retreat.

So on this bright winter afternoon, we chatter over cucumber sandwiches and drink tea with lemon and no milk, standing in the bathroom doorway while Dweezil chisels away at the bidet.

The bidet had a happy ending. The Mothers tour didn't. The previous week the band's equipment had been destroyed in a fire at their Montreux gig. Days after our interview a fan jumped on stage at London's Rainbow Theatre and pushed Zappa into the orchestra pit, causing him terrible injuries.