Not Britain, but in the USA back in classic passenger train days these were a particular problem to the streamlined "Dome Cars", with the high sightseeing lounge that projected up above the general car roofline, with glazed windows at the front, which could be (and were) broken at speed by icicles hanging from tunnels. So old photographs of F-unit diesels on affected routes can show the locos with a light steel framework hoop sticking up above the cab to the loading gauge limit, sometimes mistaken for a radio antenna, called "icicle cutters", designed to break any icicles off. They weren't a standard loco manufacturers' item, but just something fabricated locally by the railroad's workshops.