"From today onwards nobody should ever get caught short again, and we understand how important that is, be it for a young mum with children in tow, older people or friends on a shopping trip or night out," said Councillor Alan Bradley, cabinet member for street environment.

Westminster council aims to make a 'substantial impact on reducing street urination.'

"45,460 litres of urine is at risk of ending up in the city's streets and alleyways through irresponsible and anti-social behaviour," they say.

The service came about as a result of an innovation competition run by the council.

"When I'm out with friends we're always ducking into McDonalds or department stores to use their loos but we feel a bit bad about it," said Gail Knight, a 26-year-old student and the brains behind the idea..

"I thought a text service would be really useful for people on the move."

SatLav has received a warm welcome from the British Toilet Association, the campaign for better public toilets.

"It's the first fully managed service that we're aware of," said Richard Chisnell, British Toilet Association director.

"Thank heavens for Westminster's public toilets."