Toilets cost money to provide and staff, so why shouldn't you have to pay?
A fee of 20p is charged at all main London railway stations, and also at other major stations (such as Brighton).
Many British towns now charge to use their toilet facilities (e.g. 20p on Scarborough seafront). In London, it will cost you 50p to use the toilets in Parliament Square.
Most European countries have always recognised that the best way to pay for a service is to charge the people who use it. The UK is finally coming into line.
Chris