The spy who came in from the Co-op

IN THE autumn of 1992, a man called Vasili Mitrokhin fled Russia with a bag full of secrets. He had worked as a senior archivist for the KGB for much of the Cold War and had spent years meticulously copying down the Russian spy service's deepest secrets, before finally being exfiltrated by MI6 in a daring operation.

- By Gordon Corera

The secrets he brought to the West would unmask hundreds of agents who had spied for the KGB around the world. Yet it was a grandmother in a south-east London suburb who would become the most famous case and who would also cause a major headache for MI5. It is a story which points to a wider failure to appreciate the threat posed by Russia.

Mitrokhin first approached the British Embassy in Lithuania in March 1992. He turned up, looking a little like a tramp and trailing a grubby bag filled with bread and sausages. But at the bottom were pages and pages of secrets.

MI6 started passing leads from these files to K Branch of MI5. Its staff toiled away at the Security Service's gloomy offices at Gower Street, central London, and their job was to catch spies in Britain. But the Soviet Union had collapsed a few months earlier so many felt the Cold War was over and there was less to worry about from the new Russia.

At one point in the 1990s, MI5 even stopped tapping the phone of the top Russian spy at their embassy in London.

And, as ever, the Treasury was demanding budget cuts. But still they began to investigate what Mitrokhin had brought.

In June 1992, K Branch looked at one lead about an agent the KGB had run in Britain code named HOLA. That agent, it turned out, had passed important secrets from Britain's atomic weapons programme early in the Cold War. So important was this intelligence that the conveyor had been awarded the Order of the Red Banner.

Mitrokhin revealed that HOLA was an 80-year-old woman called Melita Norwood living in Bexleyheath, south-east London.

She was one of a wider group of atomic spies who had changed the shape of the early Cold War by speeding up Moscow's ability to obtain the nuclear bomb.