She was the eldest daughter of George Spencer, 4th Duke of Marlborough,[2] and his wife, the former Lady Caroline Russell.

She married Henry Agar-Ellis, 2nd Viscount Clifden (a former suitor of her sister Elizabeth), on 10 March 1792.

A portrait of the future Viscountess with her sister Elizabeth, painted in 1791 by George Romney, was commissioned by their father.

[3] It purports to show the sisters in the guise of the muses of Music and Painting (with Caroline representing the visual arts).

[6] Viscountess Clifden died at Blenheim Palace, aged 50, and was buried in the family vault of the Dukes of Marlborough, next to her mother.