This may be her article from thepeerage, "Mary Hume F, #275175, d. October 1740
Mary Hume married Nicholas Hume-Loftus, 1st Earl of Ely, son of Nicholas Loftus, 1st Viscount Loftus of Ely and Hon. Anne Ponsonby, on 18 August 1736. She died in October 1740.
She was the daughter of Sir Gustavus Hume, 3rd Bt. From 18 August 1736, her married name became Loftus.
Child of Mary Hume and Nicholas Hume-Loftus, 1st Earl of Ely
Nicholas Hume-Loftus, 2nd Earl of Ely b. 11 Sep 1738, d. 12 Nov 1769."