This is the first of two episodes about the Cambridge Five!

This week - Kim Philby, arguably the most effective spy in the history of spying.

The man running British operations against the Russians in the early years of the Cold War was actually working for the Russians himself. And there was every possibility that had it not been for one mistake, Philby would have gone on to become CSS, Chief of the British Secret Service. That mistake - sharing a flat with Guy Burgess - the subject of next week's show.

If you want to know more about Philby's amazing life, read his autobiography, MY SILENT WAR.

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