If research is right, 20% of men are capable of feeling sexual arousal to children below the legal age of consent. That is an eye-opening statistic. One in five men: in this country, that's around six million men.

This claim is backed up by eight different studies conducted between 1970 and 2006 in Europe and North America, using questionnaires and a “strain gauge” to measure “physical response”, for example to pictures or audiotaped sexual stories. The research found a significant proportion of the men in their studies – ranging between 17 and 58% – showed sexual arousal to children under the age of twelve. It is important to point out that these studies were all relatively small samples and I don't know how robustly they were designed and conducted, but they still suggest there is an important truth here that we need to learn much more about. The most important points, for me, are firstly that it seems pretty clear that most men with a sexual attraction to children, including those who go on to sexually abuse children, are not in prison but out in the community. And, secondly, that you probably know some of them.