This is the terrifying moment a window cleaner was filmed casually walking a ledge three floors up a building with no safety equipment.

The scene, which was captured on Tuesday in Belgravia, London, shows the man cleaning the outside of the windows, apparently completely unfazed by the enormous drop beneath him.

"I was having a morning coffee looking out the window and at first I was shocked and thought it was a burglar then realised what he was doing," said onlooker Pete Newman.