I thought nothing of it as there is a cat who is in the habit of jumping from one window sill to another. Then there was a louder one and a bloke landed on the window from the garages next door and looked in. When he saw me he ran out in to the garden. I'm hoping it was one of the innumerable occupants of the shared house next door who'd forgotten their keys but I think I might see if I can get the burglar alarm fixed.