'Ugly mugs' scheme improving public safety
11 April 2013 Last updated at 08:00 BST
The information gathered by a database designed to help protect sex workers is now being used to help police identify rapists and serial offenders.
The "Ugly Mugs" project works by sharing information on violent or potentially dangerous clients and known criminals, and makes it easier for the workers to report attacks.
Workers have reported 250 crimes and it is thought the information has already helped secure at least eight convictions.
Jenny Hill reports.