The Zinoviev letter, purportedly written by Soviet official Grigori Zinoviev, was released by the Daily Mail in late October 1924. In the letter, Zinoviev is alleged to have urged British communists to work towards overthrowing the British government and establishing a Soviet-style regime. The publication occurred just days before the British general election, adding to an atmosphere of fear and suspicion regarding communist influence in the UK. The Labour Party, led by Ramsay MacDonald, was quick to deny any connection to the letter, asserting that it was a forgery intended to manipulate public opinion against them.

The timing of the publication was critical as it played into the hands of the Conservative Party, depicting the Labour Party as a potential threat to national security. Conservatives utilized the letter as a campaign tool, inciting fears among voters of a Bolshevik uprising in Britain. In this context, many voters were swayed by the suggestion that communism posed a real danger, leading to a decisive Conservative victory.

The aftermath saw the Labour Party blaming the Daily Mail and the Conservatives for their loss, arguing that the letter was a major contributing factor to public perception against them. The legitimacy of the letter has been debated ever since, with many historians concluding that its publication played a pivotal role in shaping political narratives in the UK for years to come.