- Richard Tonson settled in Ireland in the latter half of the 17th century. He bought the Spanish Island estate in county Cork. Sir Bernard Burke states that his grandson, another Richard Tonson, was left a large property in 1718 by a friend of his grandfather's, Major Anthony Butler. As this Richard Tonson had no heirs he left his estates to a cousin of his mother's, Colonel William Hull, who took the surname Tonson and was created Baron Riversdale of Rathcormac in 1783. He married Rose Bernard of Castle Bernard, county Cork. Two of his sons succeeded as the 2nd and 3rd Barons. Ludlow Tonson, 3rd Baron and Bishop of Killaloe died unmarried in 1861. The title became extinct and his estates were inherited by William Thomas Jonas Stawell, second son of Colonel Alcock Stawell of Kilbrittain Castle. At the time of Griffith's Valuation the Reverend Lord Riversdale held lands in the parishes of Kilmaleery and Kilnasoolagh, barony of Bunratty Lower, county Clare and at least fifteen townlands in the parish of Rathcormack, barony of Barrymore, county Cork.