A farmer by birth, Purchase was ‘rugged in appearance and character,’ with ‘an impish sense of humor’ and a finely calibrated sense of the ridiculous: he loved Gilbert and Sullivan operas, toy trains, boiled eggs, and his model piggery in Ipswitch.

Out of a hundred birds of the same stock perhaps one will be that bird all breeders hope for – a bird of highly individual character, courageous and resourceful. Much depends on the individual bird and especially its character and intelligence.

Here, then, was a truly bizarre situation: Philby was telling Moscow the truth, but was disbelieved, and allowed to go on thinking he was believed; he was deceiving the British in order to aid the Soviets, who suspected a deception, and were in turn deceiving him.

Jens was small with a long fair mustache. Winter was enormous, roughly the size of a large door. I called them Asterix and Obelix. We got on frightfully well.

Like all truly selfish people, Kliemann believed the minutiae of his life must be fascinating to all.

The Beirut beat was a demanding one. Middle Eastern politics were as complex and volatile in 1956 as they are today. But as Philby knew from his years as a correspondent in civil-war Spain, there is no better cover job for a spy than that of journalist, a profession that enables the asking of direct, unsubtle, and impertinent questions about the most sensitive subjects without arousing suspicion.

The logistics of the operation would have boggled most minds: the American contingent alone called for 6.6 million sets of rations, five thousand crated airplanes, five thousand carrier pigeons and accompanying pigeoneers, and a somewhat unambitious 144,000 condoms, fewer than two each.

At the age of nineteen, Gordievsky took up cross-country running. Something about the solitary nature of the sport appealed to him, the rhythm of intense exertion over a long period, in private competition with himself, testing his own limits.

MI5 was careful to destroy the traffic, aware of the potential repercussions if the inhabitants of southern London realized they were being sacrificed to protect the center of the city.

And so began a bizarre situation in which Philby told Moscow the truth and was disbelieved because the truth contradicted Moscow’s expectations.