It's hardly rocket science

This is an example of odd signage on the Cambridge - Norwich train tonight. It's just twigged that it could be to direct people to another toilet if someone's hogging this, so I should give the train company a break....despite the frequent marooning that has happened to me in obscure Hertfordshire towns.

I had to keep a very low profile while snapping this as I was imagining someone emerging from the toilet as I was snapping away. I could just see the headlines: 'Ely pervert spies on commuters'.