Programme officers received eight calls in the studio and further calls have been made to the Northamptonshire Police control room.

Detective Constable Alan Fisermanis, who is leading the investigation into the serious sexual assault on the girl in a park, said: "We received a number of calls from the public during the evening after the appeal was broadcast.

"We will now be working through the information we have received to see if it can aid our investigation. I would like to thank those people who have contacted us and would urge anyone else who thinks they may know who this man is to contact us immediately."

The girl's mother told the BBC show how her disabled daughter's childhood has been ruined.

The girl was approached by a man who seriously sexually assaulted her in John Lea Park in Doddington Road, Wellingborough, at around 6pm on Thursday, August 28.

Fighting back tears in the interview for the programme, the mother said: "She has nightmares. She keeps asking me 'has he been caught, why did he do it to me?'"

She added: "She said she was going out to the park. She'd been gone for about 15 to 20 minutes when she came back to the house and said, 'mum, something's happened at the park'.

The reconstruction then showed how the man told the girl and a friend who was with her that he was a housing officer who was there about graffiti and to come down from the slide and talk to him. He then told the girl's friend to leave before sexually assaulting the teenager.

Her mother added: "My daughter has a disability and I believe he targeted her because of it. He's ruined her childhood. If she hadn't had a friend with her I think he would have done something worse."

An expert into these types of crimes, Prof Laurence Alison, told Crimewatch presenter Kirsty Young the man had had an unusual approach because of his authoratitive tone and that it was possible he has offended before.

Northamptonshire Police also released an e-fit picture of the suspect.

He is a white man, with short, spiky black hair and a greying goatee beard. He had yellowing teeth, was of slim build and is described as being short for a man. He wore a long-sleeved, light blue top and black trousers.

The man was carrying a black folder and was aged between his mid-20s and mid-40s. Witnesses can contact police on 08453 700700 or Crimestoppers on 0800 555 111.