Do not use false beards, carry plenty of spare change for the tube, and if you have to tell a taxi driver to "follow that cab", be prepared to give him a big tip.That was the advice issued to rookie MI5 "watchers" whose job it was to covertly follow and report on suspected enemy agents.The guidance is contained in a booklet issued to all new recruits to the Security Service during the Second World War.The now-declassified document is one of the exhibits in a new exhibition focusing on the work o

Do not use false beards, carry plenty of spare change for the tube, and if you have to tell a taxi driver to "follow that cab", be prepared to give him a big tip.That was the advice issued to rookie MI5 "watchers" whose job it was to covertly follow and report on suspected enemy agents.The guidance is contained in a booklet issued to all new recruits to the Security Service during the Second World War.The now-declassified document is one of the exhibits in a new exhibition focusing on the work of M15 due to open at the National Archives in Kew, west London, in the spring.