A small but severe tornado hit a residential area of north-west London on Thursday, injuring six people, ripping roofs off homes and tearing down walls. Television footage showed a trail of destruction in Kensal Rise, with trees uprooted and cars damaged by falling debris. Tornadoes are very rare in British cities.Local resident Daniel Bidgood was in his house when the tornado, which he said was about 20m, smashed his windows.