UK Intelligence Ends 20-Year Hunt for MI6 Russian Mole Without Proof

British intelligence agencies conducted an extensive 20-year investigation, known as Operation Wedlock, into a suspected Russian double agent within MI6, following a tip-off from the CIA. The investigation, led by MI5, involved up to 35 officers who undertook global surveillance, including a risky deployment to the Middle East where they operated from a CIA safe house without the host country's knowledge. Despite the scale and intensity of the operation, which included bugging, video surveillance, and following the suspect abroad, no conclusive proof of espionage was found, and the suspect eventually left MI6. The case was considered highly unusual and expensive, with fears that the mole could still be active, drawing comparisons to Kim Philby, the notorious Cambridge Five double agent. Operation Wedlock highlighted significant tensions between UK intelligence agencies, with MI5 essentially spying on MI6 to uncover the mole. The investigation concluded inconclusively around 2015, raising concerns that a Russian agent may remain undetected within British intelligence.