Brecknock was born at 48
Grosvenor Square,
Mayfair, the only child of
Colonel Atherton Edward Jenkins and his wife, Anna Isabella (
née Schoenbrunn), the niece of Sir
Ernest Cassel. She was a cousin (and life-long close friend) of
Edwina Ashley, who married
Lord Louis Mountbatten, 1st Earl Mountbatten of Burma. ==Family==