Britain is in the grip of a pickpocketing epidemic as Eastern European gangs descend on London ahead of the Olympic Games.A surge in sneak street thefts means more than 1,700 people fall victim every day – an increase of nearly a fifth in only two years, according to official crime figures released yesterday.At the same time, police warned that professional gangs from Romania, Lithuania and even South America who operate in capitals across Europe are heading to Britain, intent on cashing in on unwitting tourists at London 2012.How they do it: A member of the pickpocket gang approaches a BBC reporter investigating the rise in thefts ahead of the OlympicsKeeping him occupied: The man speaks to the victim on the pretense of needing directions...