Summary Brothers Gary and Martin Kemp turn their attentions to Britain's capital. London has always had criminals. The biggest city in Britain is like a magnet to those wanting to make a bob or two - even if that means taking the law into their own hands. Since the 1900's as many as 70 gangs have fought it out on London streets. The Second World War put pay to many of them but there was one vicious East End gang that kept alive even up to the 1960's though their origins went right back to the 19th century. Gary investigates the infamous Watney Streeters gang. A hundred years later a new wave of Asian immigrants had arrived in London. To protect themselves they formed gangs but it wasn't long before protection turned instead to extortion and then massive drug smuggling. Martin looks into the ruthless and dreaded Toot Nung gang from Southall, West London.

• Crime