Paedophilia is quite rightly one of society’s greatest taboos. Sex with children is repellent for all but a perverted minority. Middle-aged men who prey on young girls, whether they are former pop stars such as Gary Glitter or sleazy perverts in dirty raincoats, deserve everything that the law can throw at them. The internet has been a great boon for mankind but the fact that it has made it easier for paedophiles to swap their pornography and groom children for sex is a significant demerit to the world wide web.

Last week the authorities used the internet to get their own back. The Child Exploitation and Online Protection Centre published photographs on its website of five known paedophiles who have gone missing. The protection of children has to be paramount and the web can be a tool for good in this cause.

But what constitutes a child? This is the challenge thrown down by Terry Grange, chief constable of Dyfed-Powys and spokesman on child protection for the Association of Chief Police Officers (Acpo). Mr Grange says we are in danger of wrongly labelling offenders as paedophiles, thus potentially overstating the scale of the problem. Child pornography should refer to images of pre-pubescent children, 12 and under, he suggests, but not those of 13 and above. Adults who have sex with post-pubescent youngsters — aged between 13 and 15 — should not be automatically thought of as paedophiles.

Let us be clear about what Mr Grange is saying. A man who has sex with a 13-year-old girl has still committed an offence: unlawful sex with somebody under the age of 16, the age of consent. He still faces a maximum penalty of 14 years in prison. But is he a paedophile? Yes, perhaps, if he is a 50-year-old. But what about a 20-year-old having sex with a 15-year-old who looks 18? Or what about a woman and a boy who is sexually mature beyond his years? Many will be outraged that there should be different gradations of offence in this area. The onset of puberty, which for some children is well before the age of 13, does not denote psychological maturity, which may not arrive for years. Are 13 and 14-year-olds capable of making sensible decisions about sex? Michele Elliott, director of Kidscape, the children’s charity, describes Mr Grange’s views as “very disturbing”. She said: “I know he is not excusing people who have sex with children between the ages of 13 and 16 but he is saying they are not paedophiles and they bloody well are.”

For centuries the age of consent in Britain was 12, being raised to 13 in 1875 and to 16 ten years later, where it has remained. Since then, however, patterns of sexual behaviour have changed — or people have just become more honest about it. In the 1950s only 1% of young people admitted to under-age sex. This was the era when Jerry Lee Lewis, the rock’n’roll star, was hounded out of Britain after it was discovered that his perfectly legal wife (who was also his second cousin) was only 13. Now the average age at which people in Britain start having sex is 16, implying that many do so younger.

The age of consent, still as low as 13 in Spain and 14 in several other European countries and in some American states, remains a controversial topic. In Canada the government is introducing legislation to raise the age of consent from 14 to 16, while preserving the “within five years rule” for 14 and 15-year-olds, so an 18-year-old having sex with a 14-year-old would not be committing an offence.

Few are suggesting raising or lowering the age of consent in Britain, despite the fact that sexual mores have changed. The issue raised by Mr Grange is whether by labelling all adults who have sex with minors as paedophiles we risk diluting our efforts to get to grips with those who pose the biggest dangers to children, the hardcore minority. There are arguments on both sides. The debate, however, is worth having.