The Cambridge Five: A Spy Network Inside the British Establishment

In May 1951, two British diplomats, Guy Burgess and Donald Maclean, disappeared. They were not stopped at a border, left no message, and did not travel alone. They crossed France, Switzerland, and Czechoslovakia before appearing in Moscow. Britain immediately began a worldwide hunt.

The important question was who helped them leave first. Kim Philby, a senior MI6 counter-intelligence officer, was Burgess’s close friend and had worked near Maclean. He was assigned to find traitors inside the British system even though he had worked for Soviet intelligence since the 1930s. When questioned, Philby denied the crime. MI6 did not arrest him because it lacked direct evidence and quietly allowed him to leave.