Frances Crosbie, née Wesley was the daughter of Richard Wesley, 1st Baron Mornington, and the aunt of Richard, later 2nd Earl of Mornington and Marquess Wellesley, Arthur, later 1st Duke of Wellington, William, Lord Maryborough and later 3rd Earl of Mornington (father of Lady Raglan) and Henry, later Baron Cowley. She married, in 1750, William Francis Crosbie, an Irish MP.