Nearly a century ago, Britain was accused of masterminding a failed plot to kill Lenin and overthrow his fledgling Bolshevik regime. The British government dismissed the story as mere Soviet propaganda - but new evidence suggests it might be true.

For decades what became known as the "Lockhart plot" has been etched in the annals of the Soviet archives, taught in schools and even illustrated in films.

Determined to get the Russians back into the war on the Allied side, the British despatched a young man in his 30s to be London's representative in Moscow.

His name was Robert Bruce Lockhart.

At first, the well-read Lockhart seemed to be making progress on the issue but, in March that year, the Soviets signed the Brest-Litovsk peace treaty with Germany, so ending hope of them rejoining the war with the Allies.

Lockhart, it seems, had no intention of giving up.

Instead, the suggestion is, his attention was now turning to overthrowing the Bolshevik regime and replacing it with another government that would be willing to re-enter the war against Germany.

Documents show that, in June, Lockhart asked London for money to fund various anti-Bolshevik organisations in Moscow....