Cool him

look at him. A phrase frequently used when one costermonger warns another of the approach of a policeman, or when any person worthy of notice passes by. When any old lady has been bargaining with a costermonger, and leaves his barrow without purchasing, the proprietor of the barrow will call out to the rest, “cool  the delo nammow,” which, though it means literally nothing beyond “Look at the old woman,” conveys to them an intimation that she is, from their point of view, a nuisance, and should be treated as such.Costermongers' Back Slang.