No hats, no boots

When I'm up in the London office I walk past a building site. I'm always intrigued by this sign, its rather peculiar and completely alien to me as an office worker.

I guess I'm lucky, as when I limp into work after a tough weekend on my bike or running, I can crash in my office and don't have to move far. At work I'm only required to exercise my brain and not my knackered body.