She was born at Kirtlington Park in Oxfordshire, a daughter of Sir James Dashwood, 2nd Baronet, and his wife, the former Elizabeth Spencer (whose sister Anne was Duchess of Hamilton).

She married the Duke of Manchester on 22 or 23 October 1762, at St George's, Hanover Square, London, in the same year he inherited the dukedom.

[2] Their children were: Sir Joshua Reynolds painted the duchess, along with her son George, Viscount Mandeville, in about 1766.

[4] The duchess was herself an amateur artist, whose pocket book is held by the Royal Academy of Arts in London.

[6] The duke died in 1788, following which his widow received an annual pension of £3000, as official compensation for the loss of his income as Collector of Customs.