This ring commemorates Spencer Perceval, Prime Minister from 1809 to 1812 and the only British Prime Minister to ever have been assassinated. He was shot in the lobby of the House of Commons by a man named John Bellingham who blamed his financial problems on the British government. Bellingham, who was a Liverpool businessman, had spent five years in a Russian debtor's prison accused of insurance fraud after the sinking of a ship carrying cargo owned by him. Despite his appeals for help to the British authorities, he was left to his fate in Russia. On his return to Britain, he appealed for compensation for his losses, lobbying the Prime Minister in person. On his fifth failed appeal, he took out a duelling pistol and shot Perceval through the heart.

He was arrested and tried only four days later. Speaking in his defense, Bellingham asked the jury to:"Recollect that my family was ruined and myself destroyed, merely because it was Mr Perceval's pleasure that justice should not be granted; sheltering himself behind the imagined security of his station, and trampling upon law and right in the belief that no retribution could reach him." Despite this plea, he was found guilty and hanged on the 18 May 1812. In a final, gruesome touch, his body was sent for dissection at St Bartholomew's Hospital and his skull made available for phrenologists to study as an example of 'destructiveness, large'.

It was customary to have mourning rings made, enamelled with the name, age and date of death of the deceased, to be distributed to friends and family. As Spencer Perceval was a public figure, it is likely that a reasonable number were ordered. Perceval also had a large family - when he died, his wife was expecting their 20th child. She received an government annuity of £1000 and trust funds of £50,000 each were set up for their 12 surviving children. There are several other surviving rings for Perceval, including one in the Fitzwilliam Museum, Cambridge, and another in the British Museum. This ring came from the collection of Sir John Fleming Leicester, a contemporary of Perceval and a fellow member of Parliament.