[1] King was recruited by the Foreign Office as a temporary clerk in 1934 and sent to the British Delegation at the League of Nations in Geneva.
There his financial problems made him vulnerable to an approach by Henri Pieck, a Dutch citizen who was working for Soviet intelligence.
Although the official British archives only implicate King with passing information to the Soviets from 1935 to 1937, information passed on by King is elsewhere credited with giving Joseph Stalin valuable insight into British diplomatic activities aimed at containing Adolf Hitler as late as 1939.
At times this information was passed on by the Soviets to the German Embassy in London, with the aim of increasing the tension between Britain and Germany.
[2] Sometimes as little as 5 hours elapsed between a telegram being received at the Foreign Office and a summary of its contents being transmitted to Berlin.