The Surrey Comet’s publishers Newsquest led the way in efforts to ban sex adverts from the local press over Met police fears they fuelled the trafficking of women as sex workers.

The campaign picked up support from across the political spectrum and the police.

In November 2010, the Met’s head of the human exploitation and organised crime unit wrote to editors warning they could be prosecuted if they ran adverts linked to human trafficking.

Georgina Perry, of the Open Doors sexual health service at Homerton University Hospital, said fewer sex adverts in local newspapers had forced sex workers to advertise elsewhere.

She said: “It’s a market, and people have to advertise. That’s how people get customers.”

She dismissed fears the guide could stoke demand for trafficked sex workers, saying it allowed police and health workers to know where women worked, something traffickers want to avoid.

Catherine Stephens, of the International Union of Sex Workers, said research suggested 5 to 7 per cent of prostitutes were trafficked.

She countered claims the Olympics would bring more sex workers to the capital.

However, she said the speculation had increased enforcement action, reducing prostitutes’ trust in the police, and increased the risks they faced.

Selling sex is legal, but not if women work together, and men who use trafficked women are breaking the law, even if they plead ignorance.