Anne Clarissa Eden, Countess of Avon is the widow of Anthony Eden, 1st Earl of Avon, who was Prime Minister of the United Kingdom 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 on her husband's being created an earl. She is also the niece of Prime Minister Winston Churchill. Her 2007 memoir was sub-titled From Churchill to Eden.
Since the death of Mary Wilson, Baroness Wilson of Rievaulx, on 6 June 2018, Lady Avon is the oldest living spouse of a UK prime minister. She turned 100 on 28 June 2020 and is the second spouse of a UK prime minister to become a centenarian, after Baroness Wilson. She has outlived five spouses who came after her.