Certain forms of prostitution in the UK are legal. Women are allowed to work independently – selling sex from their own premises or travelling doing outcall work. But the law changes when other activities become involved.
For example, it is illegal to solicit on the street. This means prostitutes cannot work on the street and approach men for business – and men cannot approach women on the street. This is also known and kerb crawling.
It is also illegal for prostitutes to be controlled. Trafficking and forcing women to work as escorts, masseuses or call girls is also illegal.
Brothels where large numbers of women work as prostitutes are illegal.
Placing ads or business advertising sex in phone boxes is illegal. For a more detailed explanation, see this article on laws around prostitution.