British peeress and the third cousin of Queen Elizabeth II, she was styled 2nd Countess Mountbatten of Burma, Lady Brabourne. She was the elder daughter of heiress Edwina Ashley (1901-1960), a patrilineal descendant of the Earls of Shaftesbury, first ennobled in 1661, and Admiral of the Fleet the 1st Earl Mountbatten of Burma (1900-1979). She was the elder sister of Lady Pamela Hicks, a first cousin of Prince Philip, Duke of Edinburgh, and the last surviving baptismal sponsor to Charles, Prince of Wales.
Lady Mountbatten succeeded her father when he was assassinated in 1979, as his peerages had been created with special remainder to his daughters and their heirs male. This inheritance accorded her the title of countess and a seat in the House of Lords, where she remained until 1999, when the House of Lords Act 1999 removed most hereditary peers from the House.
On 26 October 1946 she married John Knatchbull, 7th Baron Brabourne (1924-2005). Later they became one of the few married couples each of whom held a peerage in their own right, and whose descendants inherited titles through both. They had eight children.
Patricia was in the boat which was blown up by the IRA off the shores of Mullaghmore, County Sligo in August 1979, killing her 14-year-old son Nicholas; her father; her mother-in-law, the Dowager Baroness Brabourne; and 15 year-old Paul Maxwell, a boat-boy from County Fermanagh. She, her husband, and their son Timothy were injured but survived the attack.
Countess Mountbatten died on 13 June 2017 at her home in Mersham, Kent, aged 93.
Link to Wikipedia biography