The drunk driver who accidentally exposed a massive Russian spy ring

On a rainy night in London on August 30, 1971, a handsome moustachioed gentleman was driving an attractive young blonde woman down Tottenham Court Road heading towards the raucous nightlife of Soho. But the romantic outing in a Hillman car just after midnight quickly took a wrong turn when police officers pulled over the couple - after becoming suspicious of the way the vehicle "wobbled" and had its lights turned off.

Likely squinting through a wound-down window into the night-time drizzle, the man behind the wheel "shouted and swore" at the officers before he was made to kill the engine. The car door slammed as the spooked good-looking passenger was allowed to leave the scene and hail a cab in the rain as the law dealt with her mysterious foreign beau. Cuffed and bundled into the back of a police car, the defiant Russian driver took the liberty of resting his feet on the back of Constable Charles Shearer's seat.

Taking up the story in his fascinating new Cold War history which reads like a spy novel, author and award-winning filmmaker Richard Kerbaj writes that Shearer later said: "Before we drove off he was lying back in the seat with his feet up on my shoulder. I turned round and said, 'What are you playing at? Take your feet off the back of my seat.' And he replied, 'You cannot talk to me, you cannot beat me, I am a KGB officer'."

Shearer dismissed the rantings of his inebriated suspect as he was well acquainted with drunks "claiming all sorts of things".

But Kerbaj's new intrigue-packed book reveals how a humble court report about this case, published only in the Daily Express the day after the man's arrest, set in motion events which would lead to one of the biggest espionage cases in British history.

Two paragraphs in this newspaper on August 31, 1971, noted: "A Russian trade delegate was charged at Marylebone Street Court, London, yesterday with driving a car while unfit through drink and failing to take a breath test." The story named "Oleg Lialine, age 34" as the offender in question, detailing how he was "remanded until September 30 on a £50 bail".

The small passage on page five would likely have gone barely noticed by the usual readers at breakfast tables and in train carriages.

But for figures in the shady world of international espionage, the moniker in black and white would have piqued their interest, even if it was spelled incorrectly.

Blue-eyed Oleg, last name Lyalin, had been working as a spy for Mother Russia, but as his arrest corroborated, he'd also been taking pleasure in a James Bond-style lifestyle in the British capital - enjoying the company of five separate women, including his wife, and trade mission colleague Irina Teplyakova.

His bungling run-in with the constabulary was seemingly the last straw and led to disgruntled Soviet spy chiefs summoning their playboy agent home. Lyalin wasn't just a bon viveur, however, he was also a member of the KGB's infamous Department V, tasked with murderous plots and sabotage against the West.

Fearing how his handlers might feel about his philandering ways, Lyalin claimed political asylum with MI5, alongside his glamorous colleague Irina.

Once under British intelligence protection, Lyalin rewarded his keepers with a deluge of information about Soviet espionage plots against the UK, including horrifying details of a scheme to poison a Scottish loch with radioactive waste to sour public opinion for the nation's nuclear programme. He also revealed he knew agents with knowledge of secret registration plates used for MI5 surveillance officers and the Royal Family.

Rumours of the defection of a Soviet spy sparked a feeding frenzy among journalists globally as they tried to unmask the agent. Meanwhile the British Government, acting on Lyalin's testimony, embarked upon the biggest ever expulsion of Kremlin spies in history, known as Operation Foot, which aimed to boot out more than 100 agents.

But even 24 hours before Lyalin was due to appear in court over his drink-driving escapades, no one had an inkling that his name was that of the turncoat spy everyone was so desperate to identify.

Speaking to the Daily Express about the unfolding drama, Bafta-winning filmmaker Kerbaj said this newspaper's reporters, Roy Blackman and James Davies, had managed to secure an interview with the Soviet diplomatic mission in a bid to wheedle out the name everyone wanted to discover.

"The reason why Blackman is important is because he was a Russian speaker, and he previously served as the correspondent in Moscow for the Express between 1967 and 1969," he said.

"Because of his skill set and understanding of that beat in general, he was obviously quite well connected with the Soviet mission, so he became the person who got the scoop." In one passage from the book, Kerbaj writes that against the backdrop of an imminent mass exodus of agents, the two Express journalists were welcomed by the Soviet mission's second secretary, Vladimir Pavlinov, on September 29, 1971.

"He toyed with the reporters at first, pretending that disclosing the defector's identity would be improper; a breach of diplomatic decorum," the book reveals. "And he maintained that posture for a little while, showing self-restraint and parrying the reporters' questions about the mystery defector with a knowing smile, before finally offering a hint.

"Pavlinov said the man in question was a 'trade official' who had recently been involved in a traffic incident that had been covered by the Express on August 31: 'His name, gentlemen, was in your newspaper,' he said, holding up his thumb and forefinger an inch apart to indicate a small story.

"It took the reporters barely any time to locate the newspaper edition that Pavlinov cited - and there, on page five, was Lyalin's name, with a variation on its spelling, 'Lialine'."

Lo and behold, the next morning, it was the Daily Express which revealed to the world the name of the defector, leading a tsunami of journalists to descend on Marlborough Street Magistrates' Court hoping to catch a glimpse of Lyalin's appearance in the dock.

Sadly for them, the machine that was the British establishment had already whirred to life and there was no chance that spymasters here were going to let one of their newest best assets out in the open.

A passage from the book reads: "Unlike his brief appearance at Marlborough Street Magistrates' Court, which had been largely ignored by the media, Lyalin's scheduled appearance at the same premises on the morning of September 30 drew journalists from around the globe, because the Daily Express had revealed his name that morning.

"It also drew the ire of MI5 and the Foreign Office, because Moscow had ruined their hopes of keeping Lyalin's identity secret.

"And in a move to aggravate the Foreign Office even further, a Soviet Embassy spokesman refused to discuss Lyalin's identity with other newspapers despite Pavlinov's deliberate leak. 'I am not in a position to confirm or deny the report, but personally I have never heard the name Oleg Lialine [sic] before,' the spokesman said."

Of course, by now journalists around the world knew well that the Daily Express would not have identified Lyalin if they had not had significant corroboration from sources inside the British Government.

And the newspaper received praise from the much-vaunted Washington Post - and even a front-page nod from the Evening Standard - for the work of Daily Express reporters exposing one of the espionage tales of the decade.

Lyalin too handed the British intelligence community a huge boost after a series of losses to the Kremlin during the 1960s.

MI5 and MI6 were still reeling from scandals, including the Profumo affair, which led to the resignation of a Tory minister John Profumo when he admitted having an affair with Christine Keeler, who was also in a relationship with a Soviet attaché.

Lyalin did pay for his actions with his freedom to a certain extent, having been sentenced to death for his betrayal by the Soviet Union in 1972, forcing him to hide for the rest of his days.

But his revelations about the planned attacks led the KGB to close one of its most deadly branches.

Moscow's sabotage and assassination programme was only resurrected under President Vladimir Putin during his rise to power in the 1990s, as Kerbaj explains: "Oleg Lyalin's defection and his disclosures led to the expulsion of 105 Soviet agents, and the information that he provided ultimately helped shut down Department V.

"The Kremlin's sabotage and assassination programme wasn't revived until Putin came to power, when he brought it back under the newly created post-Soviet intelligence agency, known as the FSB.

"And Putin's first-known Western-based target was Alexander Litvinenko who was fatally poisoned on the streets of London in 2006."

Thankfully, the Kremlin never caught up with their wayward agent Lyalin and he died from natural causes, aged 57, in 1995.

The Defector: The Untold Story Of The KGB Agent Who Saved MI5 And Changed The Cold War, by Richard Kerbaj (Bonnier, £25) is out now