Clarissa Eden, Spouse of the Prime Minister of the United Kingdom
Anne Clarissa Eden, Countess of Avon (née Spencer-Churchill; 28 June 1920 – 15 November 2021) was an English memoirist and the second wife of Anthony Eden, who served as British prime minister from 1955 to 1957. She married Eden in 1952, becoming Lady Eden in 1954 when he was made a Knight of the Garter, before becoming Countess of Avon in 1961 when her husband was created Earl of Avon. She was also the niece of Winston Churchill. In 2007, at age 87 she released her memoir subtitled From Churchill to Eden.
On the death of Lady Wilson of Rievaulx in 2018, Lady Avon became the oldest living spouse of a British prime minister. She turned 100 in 2020, the second British prime minister's spouse to become a centenarian after Wilson. She also outlived four other prime ministers' spouses who came after her: Lady Dorothy Macmillan (died 1966), Elizabeth Douglas-Home (died 1990), Audrey Callaghan (died 2005) and Denis Thatcher (died 2003).