11th May 1812: Spencer Perceval, the only British prime minister to be assassinated, shot in the lobby of the House of Commons

John Bellingham fired a single shot from a pistol, fatally wounding prime minister Spencer Perceval in the chest. Perceval collapsed immediately, and despite efforts to save him, he died shortly afterward.

3rd April 1721: Robert Walpole becomes the first de facto Prime Minister of Great Britain

Walpole was appointed First Lord of the Treasury, Chancellor of the Exchequer and Leader of the House of Commons. This made him the de facto Prime Minister and, while the title was not officially recognized at the time, Walpole wielded considerable power and influence.