Chapter One   Sex.   Anna felt a moment of panic. What if she''d already had the last time ever, and couldn''t remember it? It wasn''t like smoking, where you ceremonially flushed the rest of the packet down the loo at ten past midnight on New Year''s Eve. You wouldn''t know that it had been the last time. Had it been any good? Probably not. If it had been good, Richard wouldn''t have left. She could feel the skin contract across her cheekbones, tight with remembered pain.   She stared out the sitting room window at the rain-blurred garden, then turned back to flicking through the Sunday supplement, where everything was about sex. Dossiers were sexed up, buildings were orgasmic, even dishwashers, which had once been plain old white goods, were now transformed into sexy desirables in gorgeous finger-lickin'' hues. Then there were all the things that were better than sex. Chocolate. Yoga. Football. Gardening was the new sex, and history was the new sex, even newer than gardening. Anna sighed. If that was true, as a garden historian she ought to be awash in sex, whereas here she was, sitting in her parents'' house watching the rain dribble down the window, not even able to remember the last time she''d done it.   "Can you see them?" Anna''s mother, Valerie, bustled into the sitting room, wiping her hands on her apron, the flowery, frilly retro sort that was popular at the moment with young women playing housewife. Anna knew it was original ''50s and worn with