Broadcasters have insisted parents gave their full consent for Accrington school pupils to take part in a televised sex education programme, featuring graphic discussions about subjects including pornography.

The Hollins Technology College, on Hollin Lane, invited Belgian sexologist and former beauty queen Goedele Liekens, into its classrooms to film the Channel Four show ‘Sex in Class’, which will be screened this week.

Thirteen students aged 15 to 16 who took part in the show were given homework assignments by Ms Liekens, a United Nations sexual health ambassador, ranging from exploring their vaginas for the girls, to shaving their pubic hair for the boys.

Hyndburn council leader Miles Parkinson said he was concerned about how much parents were told about the content.

He said: “I think most people have concerns about if the parents were fully informed and if it was stretched beyond our normal sex education.

“Sex education is in the curriculum, but at the same time to go into writing essays about pornography may raise concerns.

“My concern is how the school and the headteacher relayed what was proposed and whether this was something which promoted the school and the area.”

Rev Tom Donaghey, vicar at St John’s Baxenden, raised alarms over the “growing influence” of pornography on young people.

He said: “We need to think how to manage what’s coming into our homes. It’s a growing influence and accepted as normal.”

A Channel Four spokesman said: “Statistics show that 83 per cent of young people in the UK have viewed porn by the age of 13 years old and that this is their main source of information when it comes to sex education.

“Goedele believes that many young people have an unrealistic view of sex and what is acceptable behaviour, but with the average teen losing their virginity at 16 the need for a comprehensive sex education before this age is key to empower young people to make better choices and be able to discuss the subject openly with their parents and peers.

"Both the school and parents were fully aware of the content that would be covered in the course and gave full consent for the Year 11 pupils to take part.

“The educational programme is being broadcast after the 9pm watershed and it will be made clear to viewers beforehand that it contains frank discussions and images of a sexual nature from the start and throughout.”

In a clip for the new documentary, Steve Campbell, headteacher of the school on Hollin Lane, said: “I suppose it was quite a big step to say yes we’re going to be part of this.

“But this year we’ve dealt with teenage pregnancies, we’ve dealt with inappropriate texts and without a shadow of a doubt the biggest single influence on the young people is pornography.”

As well as showing pupils tackling issues ranging from hard-core pornography to sexual pleasure, viewers will see how the pupils and their parents react, how the pupils fare in their exams on the course and if Ms Liekens will manage to get her message about sex education across.

One of Europe’s leading consultants on sex education, she was called in by the school to tackle the tricky subject, and is campaigning to have her unorthodox lessons turned into an official GCSE.

Britain has one of the highest rates of teen pregnancy and sexually transmitted diseases in Western Europe, and figures suggest that 83 per cent of children will have seen pornography by the time they reach the age of 13.

Sex education in classrooms in the UK is not compulsory and parents have the option to remove their children from sex education classes if they wish to do so.

Sex in Class will air on Channel Four on Thursday, August 6 at 9pm.