M1K3Y has posted a comment:

Actually, I’ve heard a story about these, and I thought they were stopped being used for that reason. In fact, I wonder if it’s legit?!

Apparently they had these on the tube for ages. But they had the opposite effect.

Thieves would watch as people walked past, read the sign and check that their wallet was still there.

Then the thieve’s knew *exactly* where to bump them to grab it.

So the Crime Warning Sign’s actually increased the crime rate!?!

High Risk Pickpocket Area sign, Borough Market, London, UK.JPG