British authorities announce they have uncovered the Soviet Portland spy ring in London.

The Union of Soviet Socialist Republics (USSR), commonly known as the Soviet Union, was a transcontinental country that spanned much of Eurasia from 1922 until it dissolved in 1991. During its existence, it was the largest country by area, extending across eleven time zones and sharing borders with twelve countries, and the third-most populous country. An overall successor to the Russian Empire, it was nominally organized as a federal union of national republics, the largest and most populous of which was the Russian SFSR. In practice, its government and economy were highly centralized. As a one-party state governed by the Communist Party of the Soviet Union (CPSU), it was the flagship communist state. Its capital and largest city was Moscow.

The Portland spy ring was an espionage group active in the UK between 1953 and 1961. It comprised five people who obtained classified research documents from the Admiralty Underwater Weapons Establishment (AUWE) on the Isle of Portland, Dorset, and passed them to the Soviet Union.