When we lived in north London some years back, some of these dish-cloth merchants did our road and, discovering that we were out, jemmied the front window and did a quick circuit of the house, finally making off with the video (natch) and a couple of gold fob watches, neither happily working. Call the police whenever you see anyone similarly employed; there may be one or two genuine cases, but they will just have to suck it up as far as I am concerned.