The methodology is not as rigorous this time around. For What Men Want - In Bed, Arndt recruited 150 men to write to her over the course of a year about what they want from women, which in most cases meant their wives. What they want can be summarised in two words: more sex. What they get, in the majority of the case studies, is the opposite.

This disparity has been exacerbated by technology, the Viagra revolution, as millions of men have been able to arrest the inevitable decline in their sexual potency by simply popping a pill, at about $10 a shot, of Viagra, or Cialis, or Levitra, and feeling like a 20-year-old again. Ageing men are not taking the hint from nature. Pill-popping men pervade the book, sometimes to the delight of their partners, sometimes to the consternation of women who would rather have a cup of tea.

Most of the 150 male correspondents in the book don't have much to say or aren't quoted. The load is carried by a startlingly frank minority. Some of these men are sensual boofheads, with poor communications skills and stunted ideas about sexuality. But even the boofheads suffer from a mismatch not of their own making - the changes in physiology than can make a woman drift from being sexually charged to sexually fallow.

Arndt told me her favourite person in the book is a transsexual, Anita Wolfe Valerio, who became Max Wolf Valerio, and wrote a memoir about the metamorphosis from woman to man. In The Testosterone Files, published in 2006, Valerio confronts, from first-hand experience, the divide caused by differing male and female testosterone levels: ''Now that I am Max, I see this rift, this fundamental chasm between men and women's perceptions and experience of sexuality, is one that may never be bridged. There certainly can be no hope for understanding as long as society pretends that men and women are really the same, that the culture of male sexuality is simply a conflation of misogyny and dysfunction. That the male libido is shaped and driven primarily by socialisation that can be legislated or 'psychobabbled' out of existence.''

What Men Want - In Bed is a mixture of first-hand information from a self-selected group, a survey of the literature, racy jokes, and a manual on the issues around erectile dysfunction. There are sensible insights and she comes up with one excellent slogan: ''Give it up to get it up.''