Lady Manningham-Buller worked as a teacher for three years at Queen's Gate School, Kensington, London from 1971–74, having read English at Lady Margaret Hall, Oxford, before joining the Security Service. She was recruited to the Security Service at a drinks party when someone suggested that she see someone at the Ministry of Defence. Specializing in counter-terrorism rather than MI5's then-classical counter-espionage, she was active at the time of the Lockerbie bombing by Libya in 1988. She worked for K-branch against the IRA. During the early 1980s she was reportedly one of only five people aware that Oleg Gordievsky, the deputy head of the KGB at the Soviet embassy in London, was actually a double agent.