Mary Sibell Sturt, Baroness Alington (born Lady Mary Sibell Ashley-Cooper; 3 October 1902 – 2 August 1936) was an English socialite and member of the Bright Young Things.

[1][2] Lady Mary Ashley-Cooper was born in 1902 in London,[3] the eldest daughter of Anthony Ashley-Cooper, 9th Earl of Shaftesbury and Lady Constance Sibell Grosvenor.

[1] On 27 November 1928, Lady Mary Sibell Ashley-Cooper married Napier Sturt, 3rd Baron Alington (1896–1940) at St Margaret's, Westminster.

[4] Tall and athletic, Lady Alington was a champion swimmer.

[3] Her husband died of pneumonia while on active service during World War II in Cairo and is buried there.