She founded many Roman Catholic churches and owned The Hall, Rainhill, Lancashire, and Lackham Manor, Wiltshire.
Her father was listed as a flour dealer at the time of his marriage, but he became involved in the coaching business with his three brothers at the turn of the century, made his fortune, became a landowner and benefactor.
She had been the sole beneficiary of her first husband, William Gerard; had been amply endowed with the residue of the estate of her second husband, Gilbert Stapleton; and was the inheritor of her father's lands and, on the death of her mother, occupied Rainhill Hall (later it became a Catholic retreat centre known as Loyola Hall).
[6] She had the means to keep the two mansion houses and estates going, and to give away her home at Ditton Hall, Widnes to the Jesuits in exile from Germany in 1872.
Mary owned mines, quarries, woodlots, farms and their dwellings, and had a financial portfolio of stocks and shares.
[8] Mary changed her last name to Stapleton-Bretherton by Royal Licence in September 1868[9] and was made a Marchesa Romana by Pope Pius IX in 1873.
[11] Her main heir was her first cousin once removed Frederick Annesley Stapleton-Bretherton (1841-1919) whose family then occupied Rainhill Hall as well as property in Hampshire.