A HARD-HITTING documentary laying bare Cheltenham's illegal sex trade has provoked outrage and revulsion, police said last night.

The Hunt for Britain's Sex Traffickers, which was screened on Channel 4 over the past three evenings, drew millions of viewers.

Covering the country's biggest ever operation against people-trafficking, the programme showed Gloucestershire police cracking a sleazy underground network of brothels.

Detectives who led the blitz say there has been a massive response from viewers expressing revulsion at the footage, which includes interviews with women forced to have sex with up to 10 clients a day.

Det Supt Alex Drummond said: "We have had comments poring in from people who saw the documentary. Most people said they thought it was extremely powerful.

"Hopefully it will help to change attitudes towards this kind of crime and encourage less tolerance from people who know it is going on.

"Those who have seen the programme will now be more aware of the suffering it causes and reflect that this is not something they want going on in their town."

Dubbed Operation Pentameter II, the series of coordinated swoops across the UK resulted in 528 arrests and 167 victims being saved, many of whom were trafficked into the country from Asia and Europe.

Armed units burst into more than 800 premises and seized more than £500,000 in assets.

In Cheltenham up to 100 officers sprung surprise raids at brothels in Evesham Road, Normal Terrace and London Road. By tracing bank account details, they were able to pinpoint exactly who was profiting from the seedy enterprise, leading to numerous convictions.

Police said the operation marked a turning point in the way they dealt with vice crime.

"It gave us an infinitely better understanding of how people involved in this kind of crime operate," added Mr Drummond.

"With the know-how we now have, I hope there will be no need for a Pentameter III.

"We will now be targeting this on a day-to-day basis, targeting illegal brothel owners and people-traffickers in the same way as we target any other serious offenders.

"I hope the programme sent out a clear message that this kind of crime will not be allowed to escape under the radar."

Laura Craddock, fundraising officer for Eaves' Poppy Project, which supports women trafficked into prostitution, said: "Although the series only scratches the surface of these trafficking networks across the UK, we hope it will inspire the public to support projects which try to bring justice for women who are forced to work as modern day sex slaves."

Channel 4 bosses said they were delighted with the viewing figures, which were on course to top three million before last night's final episode.