There is a horror movie, produced either in GB or in the US. Probably in England. The production year was 1978 or 1979. Well, There is a person with a yellow raincoat and yellow hood. Probably with a mask over the face. This person stab several persons in a block of flats. Don't know if the raincoat murder is a man or a woman. But as far as I know, it seems to be a pretty tiny person. There is a scene in the movie when somebody place out bugs on the floor in a fat man's flat. Then, a litte while later he is stabbed in the stomach. The surroundings in the movie reminds me of England by the bad weather in the movie, but i'm not sure.

If someone recognize what movie i'm talking about feel free to post a message! Thanks!