She was the only surviving daughter and sole heiress of Samuel Rolle, MP (1646–1719), of Heanton Satchville, Petrockstowe, by his second wife, Margaret, daughter of Roger Tuckfield, of Raddon Court, Devon, a junior branch of the Tuckfield family of Little Fulford, near Crediton.
Apart from many lucrative manors, she also inherited from her father patronage of the Rolle pocket borough of Callington in Cornwall, to which in 1761 she nominated as MP her Devon agent Richard Stevens (1702–1776), of Winscott, Peters Marland, adjacent to her estate at Petrockstowe, and brother-in-law of a distant cousin, Henry, 1st Baron Rolle (1708–1750).
[citation needed] Margaret Rolle married twice: The Countess of Orford eloped to Florence with Samuel Sturgis, Fellow of King's College, Cambridge.
Her friend, the Countess of Huntingdon (formerly Lady Selina Shirley), later declared that she was "a woman of very singular character and considered half mad.
[2] The heirs male of the 3rd Earl of Orford tried to claim the Heanton Satchville estates, but after a long and complex court case involving the examination of entails made by Sir Samuel Rolle, these lands were adjudged in favour of the Trefusis family.