The Jamaican and black British criminals are among a hard core of 200 crack-cocaine dealers and gunmen in London who belong to about 20 gangs or groupings. Detectives have also discovered that Jamaican drug dealers are using new covert routes into Britain to smuggle gangsters and shipments of crack cocaine. Violent criminals are switching from the traditional passages from Jamaica to Heathrow and Gatwick. They are using a French-owned Caribbean island, with stop-offs in Europe, to hide from the police and immigration officers tracking them. The Jamaicans, while organised, do not operate in gangs, the senior officer says. But Yardies from the same districts in Jamaica have tended to stick together and moved to the same parts of London and other cities, including Bristol. The crack dealers have already moved into Manchester and Liverpool in significant numbers. most feared and brutal gangsters in Britain: