She was the only daughter of Colonel John Jacob "Jack" Astor IV (1864–1912) who died in the sinking of the Titanic and Ava Lowle Willing (1868–1958).

Her paternal grandparents were real estate businessman and race horse breeder/owner William Backhouse Astor Jr. (1829–1892) and socialite Caroline Webster "Lina" Schermerhorn (1830–1908), while her maternal grandparents were businessman Edward Shippen Willing (1822–1906) and socialite Alice Caroline Barton (1833–1903).

They lived in her townhouse on Grosvenor Square in Mayfair, London (from October–April) and her country estate, Sutton Place in Guildford, Surrey (from May–September), and she was educated at Notting Hill High School.

[14] At the time of their wedding, Harding, a cousin of Maxwell Eley, was serving with an anti-aircraft battery in the British Army.

[18] Astor died of a stroke in her 219 East Sixty-first Street apartment, Manhattan, New York City, on July 19, 1956, at age 54.