The author shows how Margaret Thatcher overcame her earlier extreme scepticism about the possibility of radical reform within the Soviet Union. She was persuaded in 1983 that Great Britain should engage with the Soviet Union and Eastern Europe as the best way of encouraging peaceful change. The most important manifestation of this policy shift was the invitation to Mikhail Gorbachev to visit Britain in 1984. That was the beginning of an argumentative but constructive political relationship which developed into an unlikely friendship between the ‘Iron Lady’ and the last General Secretary of the CC of the CPSU. Margaret Thatcher described her visit to the Soviet Union in 1987 as the most important of all her foreign excursions. She returned home convinced that important change was underway. A combination of Mrs. Thatcher’s good relations with Gorbachev and her status as President Ronald Reagan’s favourite foreign leader enabled her to play a constructive role in the ending of the Cold War.