She married the 2nd Baron Ampthill, a civil servant, in 1894.Lord Ampthill served as Governor of Madras from 1900–06.
She was appointed a Companion of the Order of the Crown of India in 1900 and awarded a gold Kaisar-i-Hind Medal in 1906.Lady Margaret first became friends with Queen Mary in 1891, when she was known as Princess May.
Lady Margaret was appointed a Lady of the Bedchamber to Queen Mary in 1911, but was honoured by four monarchs for her charity work.In 1918, she was appointed a Dame Grand Cross of the Order of the British Empire for her work with the Red Cross during the First World War and a Dame Grand Cross of the Royal Victorian Order in 1946 for her work as aa courtier.
She was also a Dame of Grace of the Venerable Order of Saint John of Jerusalem.After her death, Viscount Templewood eulogised her in The Times and commented on her friendship with Queen Mary: