On a hot autumn evening in Tehran in 1981, two spies sat drinking vodka in a small white-tiled bathroom. One, Ian McCredie, was British; the other, Vladimir Kuzichkin, was a KGB major, more than six feet four inches tall and so broad that the wicker laundry basket beneath him creaked. The cold taps ran into the bath and basin, while a radio played to mask their voices from Iranian listening devices. If they were overheard, both men risked arrest, torture and perhaps execution.The Russian had already offered to betray the KGB, and possessed a secret of potentially enormous value. It appeared that Soviet-backed communists were preparing for the possibility of seizing power in Iran and inviting in the Red Army, giving Moscow access to the country’s oilfields and the ports on the Persian Gulf. Kuzichkin revealed what he wanted in exchange; he believed Western medicine could cure something that was destroying his marriage – erectile dysfunction.Ben Macintyre’s terrific new book, Redwood: The Untold Story of the Cold War’s Most Extraordinary Spy, begins here, with a scene that dismantles the idea that history is shaped only by grand strategy, ideology and powerful states.“I was first told about it ten years ago, and I didn’t believe it,” Macintyre tells me. “I love this story. One man’s very private, very secret problem, and it can be a hinge of history.”Kuzichkin’s vulnerability had roots far deeper than his unhappy sex life. Born in Moscow in 1947, he was raised as the son of Andrei Kuzichkin, a violent, alcoholic and embittered KGB officer. At 22, he discovered that Andrei was not his biological father. His real father was Georgi Larkin, a construction engineer of Irish ancestry who had died in Siberia before Vladimir could meet him. The revelation fractured his sense of identity, but also offered the possibility that he could become somebody else.He joined the Communist Party and married Galina Kokosova, a diminutive, secretly religious young woman whom he adored. After university, he entered the KGB and was eventually posted to Iran, where revolution had swept away the Shah and replaced his regime with the Islamic Republic of Ayatollah Khomeini. The country became a crucible of violence, conspiracy and espionage, as Islamists, nationalists and Marxists fought to determine its future while Iran was also at war with Iraq.Kuzichkin served under diplomatic cover as a vice-consul, but his real work included liaison with the Tudeh, Iran’s communist party. The Tudeh received Soviet money and direction, and had constructed a clandestine network extending into the armed forces. With the USSR already occupying neighbouring Afghanistan, Western governments feared that a communist coup in Tehran could bring Soviet forces to the Gulf and, in the worst scenario, set the superpowers on a path towards nuclear confrontation.Vladimir Kuzichkin with the McCredies (McCredie Family Archives)“From every point of view, this was a genuine threat. A real fear,” Macintyre says.By the time he approached the British, Kuzichkin had become disgusted by Soviet corruption and the KGB’s manipulation of Iranian politics. But Macintyre does not turn him into a spotless ideological dissident. His motives were political, psychological and painfully physical.He was drinking heavily, feared losing Galina and had developed an almost mystical belief that Western doctors possessed a pill denied to Soviet medicine. If MI6 could restore his potency, he imagined, it might restore his marriage too.His first approach was appropriately confused. Kuzichkin walked into the British embassy and announced to the diplomat Nicholas Barrington: “I am KGB. I wish to defect to UK.” He had selected Barrington because the KGB mistakenly believed the flamboyant, impeccably dressed envoy must be MI6’s man in Tehran. But Barrington was not a spy at all. The offer was passed instead to McCredie, a young intelligence officer working under diplomatic cover, who had to decide whether this implausibly valuable Russian was genuine, a KGB “dangle”, or bait in an Iranian trap.MI6 gave Kuzichkin the codename REDWOOD, inspired by his immense height. McCredie concealed him beneath a blanket in the back of a Land Rover to bring him into the British compound, where the bathroom became their improvised safe house. MI6 supplied pills – which were nothing more than vitamin tablets as this was a pre-viagra era – and an elderly Minox camera. Kuzichkin would then return exposed film in cigarette packets during fleeting “brush contacts”. Every encounter risked detection by the KGB or Iran’s competing security organisations.“McCredie is an extraordinary figure,” Macintyre says. “You think you’re getting to know him, and then you’re not sure that you know him at all. Clearly this operation was the most important part of his life, and his relationship with Kuzichkin was the defining relationship of his life. The dangers he was under were absolutely terrifying – if he had been caught… The stakes were very high.”Vladimir Kuzichkin and Galina at the National Botanical Gardens, Tehran (Galina Kokosova Archives)That is partly because REDWOOD demonstrates a central truth of agent-running: spies are recruited through human needs, which seldom fit the tidy acronym of money, ideology, coercion and ego, often known as MICE. Kuzichkin wanted to challenge a system he had come to despise, but also to save his marriage to the woman he loved. His courage was inseparable from shame, loneliness and fear.He began supplying information about KGB personnel, secret communications, Soviet operations and the Tudeh underground. The material was extraordinarily valuable, but it also posed an increasingly dark question: who would ultimately use it, and to what end? As the operation moves towards its most dangerous phase, Macintyre transforms a tale of brilliant tradecraft into a moral inquiry. To reveal the outcome would be a plot spoiler, but the legacy of the operation remains fiercely disputed.“There is still some ambivalence about the story,” Macintyre says. “Some say that it was totally justified, the more gung-ho brigade. Others say that the butcher’s bill was too high. But you have to remember that this wasn’t MI6 acting rogue. It was ultimately a political decision.”Interestingly, the service made no attempt to obstruct his research. “MI6’s attitude to secrecy is changing,” he says. “I think it’s much more realistic these days. But nobody wants to be the next Tomlinson” – a reference to former MI6 officer Richard Tomlinson, whose disclosures led to prosecution and years of legal conflict.The remark points to one of Redwood’s most unsettling themes. Intelligence operations do not end when the secret has been obtained or a case officially closed. Information develops an afterlife, passing into other hands and colliding with calculations its source may never have anticipated. A tactical triumph can become a strategic disaster; the enemy of an enemy may prove still more dangerous.(Viking)That ambiguity makes a story from the 1980s feel disconcertingly current. The apparatus of espionage has been transformed by satellites, cyberwarfare and mass interception, yet Macintyre believes human intelligence – Humint – has become more valuable today rather than less.“The reality is that espionage is more important than it has ever been,” he says. “There’s been this feeling that cyber will take over, and that espionage is now basically all about interception. But Humint is now more important than ever. Sigint is very easy to corrupt. We are going back to a more analogue way, a more old-fashioned way.”Signals intelligence may capture what an organisation is saying, but a human source can reveal whether its leaders believe it, whether subordinates are merely supplying the answers demanded of them, or whether an entire intelligence apparatus is lying to itself. Macintyre sees Vladimir Putin’s assault on Ukraine as the supreme modern example.“The biggest intelligence mistake was Putin invading Ukraine,” he says. “He was told by the FSB that he could almost walk in.”Russia has also revived the “illegal”, an intelligence officer living under a false civilian identity without diplomatic cover. “There are spies among us, and there are illegals all over the place,” Macintyre says. “This is something straight out of the Cold War playbook. There are more illegals operating in the West than during the time of the Soviet Union.”Like the best of Macintyre’s books, Redwood is less concerned with the machinery of espionage than with the unruly people caught inside it. States may devise codenames, doctrines and clandestine networks, but secrets are carried by vulnerable and messy human beings. The most sophisticated intelligence system can still turn upon love, vanity, terror or humiliation – and the course of history upon a whispered bargain in a Tehran bathroom.Redwood is published 10 September. Ben Macintyre will be live on stage at the How To Academy on Tuesday 8 September, 7:30pm – 8:45pm, at the Emmanuel Centre, Marsham St, London, SW1P 3DW.