While minor offences such as soliciting are still pursued, the police shifted their focus to protecting sex workers and building relationships of trust with them.

In 2006, Merseyside police was the first and so far only force in the country to declare crimes against sex workers as “hate crime”.

The results have been dramatic. In the five years before the new way of working began to take effect in 2007, there was just one conviction for a series of assaults against sex workers.

Now the overall conviction rate for crimes against sex workers is 84%, with a 67% conviction rate for rape. The national average conviction rate for rape is just 6.5%.

Last year in Liverpool there were 10 convictions for rape and several more men have been charged and are awaiting trial in 2011, some for multiple rapes as well as other violent offences.

Detective Superintendent Tim Keelan said: “These women are very vulnerable, and our priority is to protect them. We are seeing interest from a number of other police forces in our model and we have set up a Unity team – the only joint police and CPS team in the country – to help prosecute offenders.”