Oleg Lyalin… the defector who saved British intelligence and unsettled the Kremlin

27th August 2025

3 minutes read

Oleg Lyalin… the defector who saved British intelligence and unsettled the Kremlin

At the height of the Cold War, while Britain lived under the constant threat of Soviet infiltration, a KGB officer came forward with stunning revelations about sabotage and assassination plans.

The central question facing the leaders of MI5, Britain’s domestic counter-intelligence agency, was clear: could he really be trusted?

The story began in September 1971, when Oleg Lyalin, a young KGB officer, knocked on the door of a police station in North London, asking to be put in contact with MI5. For two years, he had lived undercover in Britain, posing as a “textile expert” with the Soviet trade mission. Believing – mistakenly – that his cover had been blown, he decided to defect.

He was quickly moved to a safe house, where he began to reveal explosive secrets: contingency plans developed by the KGB’s sabotage and assassination unit – the so-called “Fifth Directorate” – that targeted the UK in the event of war. These included assassinating political leaders, sabotaging railways, contaminating coastal waters with radioactive waste, and disrupting food supplies.

Unexpected personal motives
Unlike the stereotypical defector seeking asylum or money, Lyalin was driven by deeply personal reasons. His aim was to be officially expelled from Britain so he could return to Moscow and divorce his wife Tamara, with whom life had become unbearable due to marital disputes, late-night parties, and extramarital affairs.
A later CIA report even noted that Lyalin offered to provide intelligence in exchange for being declared persona non grata, believing such a move would earn him credit with the KGB and allow him to finalize his divorce.

A trust crisis with Washington
His sudden appearance aroused strong suspicion within MI5, which still bore the scars of notorious betrayals by British double agents like Kim Philby and Anthony Blunt. The CIA had also repeatedly warned of Soviet tactics using “false defectors” to penetrate Western services.
The MI5 Director-General at the time, Martin Furnival Jones, faced a dilemma: inform the Americans, thereby risking exposure of the operation, or secretly test Lyalin’s credibility. He chose the latter. A lengthy process of questioning and surveillance confirmed much of what Lyalin had disclosed.

Names and plans unveiled
Over time, Lyalin revealed more details. He handed over the names of KGB and GRU (Soviet military intelligence) officers operating secretly in Britain. He spoke of plans to use the North Yorkshire coast as a landing site for sabotage teams, and pointed to a network of local agents equipped with radio sets to support future operations.

The decisive moment
In August 1971, Lyalin was arrested for drunk driving. Days later, Moscow urgently recalled him. That was the moment he made his definitive choice: to formally defect and request asylum in Britain, alongside his mistress, Irina Teblyakova.
His intelligence proved invaluable. London launched “Operation Foot,” the largest diplomatic expulsion in British history, expelling 105 Soviet intelligence officers. It was a crushing blow for the Kremlin, forcing the KGB to dissolve its Fifth Directorate and conduct painful internal reviews. For the first time in years, MI5 had the upper hand.

A lasting climate of suspicion
The defection threw the KGB into a state of paranoia. Officers were required to report any suspicion about their colleagues, mirroring the climate of distrust that had long haunted British and American intelligence. Yet doubts persisted. James Angleton, the CIA’s legendary counterintelligence chief, traveled to London claiming Lyalin was merely a “planted agent.” The British, however, dismissed his assertions, citing the tangible results obtained.

Epilogue and legacy
In July 1972, a Soviet court sentenced Lyalin to death in absentia. Nevertheless, he lived under a new identity in northern England until his death in 1995.
Russia’s assassination campaigns, however, did not end. In 2006, Alexander Litvinenko was murdered in London with radioactive polonium, and in 2018, Russian operatives attempted to kill Sergei Skripal using the nerve agent Novichok.