Over nine years, the former MI6 officer handed British secrets over to the Soviet Union, betraying at least 40 British agents in Eastern Europe. Jailed in London in 1960, he pleaded guilty to five counts of passing information to the Soviet Union. Six years later, he broke out of jail and fled to Russia. There, he received a hero’s welcome along with fellow members of the notorious Cambridge ring of double agents, led by Kim Philby, that the KGB planted in the heart of British intelligence. Notable fellow members were Guy Burgess and Donald Maclean. Their extraordinary careers as traitors have provided endless scope for films and books.