A former detective who led a project tackling child prostitutes' pimps in Wolverhampton 10 years ago has said lessons have not been learned.
Child pimping remains a big problem, Panorama has found
A BBC Panorama investigation has found girls as young as 12 being groomed for prostitution in the UK.
Lyndon Whitehouse, a former detective sergeant with West Midlands Police, said the 1990s project secured very high conviction rates.
But it was discontinued and child pimping prosecutions remain low.
There have been only 12 since the project ended in 1999, although the law has been changed to make grooming an offence.
The government estimates 5,000 British children are currently working as prostitutes in the UK.
The project worked by taking child prostitutes off the streets and targeting their pimps and also tracked gangs as they trafficked young girls from city to city.
But the project, which was also carried out in Nottingham, was not followed up by the Home Office.
Mr Whitehouse told Panorama: "Over an 18-month period we investigated 91 cases.
"In 71 of those we uncovered evidence of coercion and exploitation.
"In 35 cases we brought a prosecution, 35 individual adults were charged with offences in connection with the exploitation of children for prostitution and virtually all of those people were convicted."
He added: "My view is that the only way to stop a really, really serious crime is to have dedicated units as we do now with domestic violence and things like that which historically was a subject which was never recognised."
The BBC has found only two police forces with dedicated units tackling the problem.
Home Office minister Vernon Coaker said some improvements had been made in the way the issue was tackled.
He said: "I'm saying we have done better in terms of the support we give to victims, if we talk to police and prosecutors we know it's a difficult area to prosecute.
"Part of the problem is how we give the confidence to the victims in order to give evidence."
The Home Office said that pimping children would be covered in new police targets and a warning video would be produced for use in all schools.
Teenage Sex For Sale: Panorama is broadcast on BBC One at 2035 GMT on 27 March 2008.