The last chapter of Britain’s most infamous spy scandal can finally be told as the release of security service files reveals the long hunt for Kim Philby, the notorious KGB mole inside MI6, who spied for Russia for three decades.

Philby was recruited by the Soviet intelligence service in 1934, soon after leaving Cambridge University. He joined MI6 (also known as the Secret Intelligence Service, SIS) during the war and rose swiftly through the ranks, passing on to Moscow every secret he could gather, with murderous results. In 1963 he was finally exposed while working as a journalist in Beirut, and fled to Moscow, where he died in lonely alcoholic exile 25 years later.