"Claire knows all about her dad's first time," Sarah wheedles reproachfully. "No!" I reply. "We'll grow up inhibited," Ginny warns, not realising that a little inhibition is what I am praying for round here. One of the best things about sex, in my middle-aged opinion, is that it is a private experience. The more private the more potentially profound. I shall always be glad that I dodged all attempts at sex education in my youth. Sex was for dreaming about in the long grass on a heavy summer's afternoon. It was not a subject with which to plague your parents when they're trying to earn a living.
"I don't think I'll have sex at university," says Sarah, sighing heavily against my office door. "I want to go to a really posh hotel. But I suppose if everyone's having it at 16 I'll have to."
"You don't want to do it too soon," Ginny cautions her. "Or everyone will think you're a tart."
"Yes but if you don't do it at all boys think you're frigid." They cannot leave the subject alone. They fiddle with it constantly in the hope of discovering reassurance or titillation. "What d'you think the best thing about sex is?" says Sarah for the umpteenth time.
"Listen," I say, switching off my screen. "Shall I tell you what the best thing about sex is?" They are agog and yet embarrassed too. "Many years ago I discovered that the most wonderful thing about sex is that it's entirely optional. Now can I get back to work?"
Adrian Mourby's column will return on September 3.