This looks like a tricky, and unnecessarily risky, manoeuvre...

Safety blunder

Thanks to Sara McKinnon for this image. She says: "I took this in Clapham, just off the Common.

"It seems ladders are for losers – these boys know the best thing to do is balance on top of a van parked in heavy traffic manhandling a heavy load through a window while suspended above spiked railings: obviously."