"A woman said she was looking for the toilet," says John. "I told her to get out. She replied 'I'm pregnant', so I escorted her downstairs, where
a couple of blokes were waiting."
John has since spent £40 on a very secure mechanical lock and another £40 to have it fitted. You need a three-digit code to open it. And here's a practical tip from him to anyone else buying such locks. "Always press the clear key first before putting the code in, just in case anybody has had a go at it which would queer the sequence. Wherever you get it, B&Q or a key fitter, they don't tell you this so you only find out through experience."