“The changes, physical and mental, to young children over the past few years are terrifying. I’m relatively young and fairly unshockable, but the language some of the boys use is staggering. You think, Christ, how do they know that? And the girls come in wearing cropped tops and bootcut leggings - I’ve even seen seven-year-olds applying make-up in the toilets.”

West London primary teacher

The London authority which runs the school at the centre of the recent Old Bailey rape trial is to launch a massive review into the sexuality of primary schoolchildren.

Last week a jury at the Old Bailey acquitted four boys, three aged 10 and one aged 11, of indecently assaulting a nine-year-old girl classmate in the toilets of a west London primary. The judge had earlier ordered that previous charges of rape be thrown out. A fifth boy, nine at the time of the alleged attack, was too young to stand trial.

The school will now close at the end of the academic year, with all 104 pupils transferred to “more popular” schools in the area. The Jamaican-born girl accuser already attends a new school. The five boys were expelled the day the allegations came to light. It is believed the nine-year-old is attending a new school, while no long-term alternatives have been found for the others, although the authority says they are still receiving an education. All six families are now subject to social service inquiries.

An authority spokesperson said: “We have to move on. What’s important now is to support other schools in the area. It would have been difficult for us to close the school just because of the trial, but we can’t pretend it had no bearing. The closure application states two reasons - poor academic performance and low pupil numbers. But neither of those were helped by the national publicity. ”

The school’s former head, who had 17 years’ experience and previous posts in the inner-city boroughs of Brixton and Camden, went on sick leave two days after the alleged rape, and never returned. Her contract was severed after she agreed to sign a confidentiality agreement, and she received a Pounds 21, 786 pay-off.

In court she said she had never before heard children using such “highly-developed” sexual language as in the playground of her school. And despite the acquittal the defence never denied that sexual activity or “horseplay” took place.

The head admitted the word sex was written in schoolbooks and that children often taunted each other as gays and lesbians. She blamed the influence of popular culture and rap music. An internal school report revealed that Class 5, in which all the pupils were taught, was widely regarded as the most difficult.

Fighting and bullying were commonplace. And although two of the boys had special needs, the girl, whose behavioural problems included arson, had been regarded by staff as a storyteller and fantasist.

Dr Jocelyn Emama Maxime, director of a private children’s clinic, has long argued that children from ethnic backgrounds struggle to get help from the educational psychology services.

She said: “They are all too readily expelled instead of receiving counselling. I often have education authorities refer children at the 59th minute, children on the point of suicide who should have been offered help years ago.”

Last year the school’s final inspection report found poor academic performance a bigger problem than behaviour. The authority admits that the sex talk and games should and probably could have been prevented but insists it is “unfair to suggest this was a school running out of control”.

The spokesperson said: “A lot of inner-city schools have these kind of behavioural or bullying problems, apart from the poor performance it didn’t really stand out as being particularly that bad. People look for scapegoats, but there is no way anyone could have foreseen the signs that this would happen.”

A primary teacher at a different school in the borough says: “We’ve all been shocked to the core by what’s happened. It really is ‘there but for the grace of God go I’. The changes, both physical and mental, to young children over the past few years are terrifying. I’m relatively young and fairly unshockable, but the language some of the boys use is staggering. You think, Christ, how do they know that? And the girls come in wearing cropped tops and bootcut leggings - I’ve even seen seven-year-olds applying make-up in the toilets.”

The assumption that children are growing up faster is borne out by the physical evidence. A generation ago the average age of puberty was 13, today it seems closer to 10 or 11.

Another LEA insider said: “We’re facing the hard facts about primary schoolchildren and sex because frankly, after this, we have no choice. But I do think other LEAs should do the same. I know it’s difficult - how early is early and how do you persuade parents sex education is OK for small children?

“We might come up with a few answers, but really no one knows how to stop this happening again.”