Listen to Ben Macintyre's theory on the case of Litvinenko

Preserved in the permafrost of the Cold War is a piece of advice given by Pavel Sudoplatov, Stalin’s master spy, to an apprentice agent. Sudoplatov’s career in the Soviet secret service spanned three decades of Stalinism, and few understood better the brutal and complex psychology of spying.

When seeking to recruit a spy, Sudoplatov advised his underling that one should “search for people who are hurt by fate or nature — the ugly, those craving power or influence but defeated by unfavourable circumstances. In co-operation with us, all these find a peculiar compensation. The sense of belonging to an influential, powerful organisation will give them a feeling of superiority over the handsome and prosperous people around them.”

This comes close to a perfect definition of the mentality of espionage. It brings together such different characters as Kim Philby, the upper-class British traitor, Melita Norwood, the octogenarian British KGB mole, and Alexander Litvinenko, the former KGB officer murdered last week with radioactive polonium-210. Spies spy for many reasons: ideology, greed, sex, revenge, honour, fear of blackmail. As a trade, espionage attracts more than its share of the damaged, the lonely and the plain weird. But all spies crave undetected influence, that secret compensation. Espionage may spring from patriotism or treachery, but ultimately it is an act of imagination.

Litvinenko’s deathbed statement was that of a man settling grievances, acutely aware of the drama of his own, horrible end, and of his own moral superiority: “As I lie here I can distinctly hear the beatings of wings of the angel of death . . . May God forgive you [Vladimir Putin] for what you have done, not only to me but to beloved Russia and its people.”

John Masterman, the Oxford academic who masterminded the running of double agents for MI5 during the Second World War, made a close study of the spies that passed through his hands. He concluded: “Certain persons have a natural predilection to live in that curious world of espionage and deceit, and attach themselves with equal facility to one side or the other, so long as their craving for adventure of a rather macabre type is satisfied.”

Even as he lay dying, Litvinenko demonstrated a macabre excitement at his own martyrdom. Few professions (with the possible exception of the Mafia, aping its fictional re-creation in The Sopranos) are more acutely aware of their own mythology, and in thrall to it. “It was like living in a spy novel,” John Symonds, a former policeman turned KGB spy, once observed. “The whole business was a game.”

For decades, the KGB operated its spy networks on principles represented by the acronym MICE: money, ideology, compromise (as in blackmail) and ego. By far the most important was ego. Spymasters on both sides of the Iron Curtain awarded their spies exotic codenames, the better to flatter their self-esteem. Ideological belief is a useful attribute in a spy; but belief in one’s own importance is essential.

Alongside the arrogance of the spy lies a remarkable capacity for self-delusion. The espionage world has always drawn people with a tenuous grip on reality: fantasists, paranoiacs, conspiracy theorists, fraudsters and fakers. The British secret service, in particular, seems to have attracted a disproportionate number of people who were at best eccentric, and at worst entirely mad. Yet an overactive imagination is not unique to the British spy.

Sudoplatov himself was prone to wild exaggeration: his memoirs published in 1994 were at least partly fiction. Malcolm Muggeridge (former intelligence officer and journalist) maintained that “intelligence agents, in my experience, are even bigger liars than journalists”.

One thinks of Anthony Blunt, dwelling in his privileged world of deceit: the dedicated Marxist who was also Surveyor of the King’s Pictures, pillar of the Establishment and KGB spy, a most clubbable man, closet homosexual, closet traitor. Blunt kept his contradictory lives locked in different hidden compartments, an act of deception on an extraordinary scale. Cool and desiccated to the end, Blunt feasted in secret on his own peculiar compensation.

Melita Norwood, Agent Hola, “the Spy who came in from the Co-op”, is often regarded as a different sort of spy. For 40 years, she made chutney in her suburban home, worked at the Non-Ferrous Metals Research Association, and fed secrets to the Soviet Union at the time Moscow was building its own nuclear bomb. Norwood said that she had spied for purely ideological reasons, but she wanted to affirm her importance by proving a point.

Shortly before she died, this grandmother and secret holder of the Order of the Red Banner made a most revealing remark: “I though I’d got away with it.” For most of her life, the humble secretary and inconspicuous old biddy had got one over on the handsome and prosperous people around her, and that was her principal reward.

In his latest novel, Restless, William Boyd precisely identifies the quality of intellectual superiority that is the hallmark of every spy. Like Blunt, his traitor hides deep within the Establishment, arrogant in the secret power conferred by treachery: “He was laughing all the time. All the time, laughing at them all.”

That, perhaps, was also the peculiar compensation in Litvinenko’s self-penned epitaph. He knew he was dying, but the battle at the end was less to do with politics or morality than having the last word. As the poison killed him, he wanted to leave a poisoned message to the man he thought had administered it: “You may succeed in silencing one man, but the howl of protest from around the world will reverberate, Mr Putin, in your ears for the rest of your life.”

Like all spies, Litvinenko was determined to have the last laugh.