Sir Knight Ieuan took over his grandfathers Knights of St. John's known as Ieuan's Hospice. Was 9th Lord of Grosmont, M.A. Oriel College, Oxford. (The following marriage may or may not be correct). Married Cecilia, daughter and heir of Sir Robert de Clare, 2nd son of Richard, 4th Earl of Hereford, by his wife the Lady Amina, daughter and co-heir with her sister Isabel (1st wife of King John) to William, Earl of Gloucester. Other possible wives were Crisli verch Gawdyn; Cecil verch aydan and Cecil Llewely. NOTE:Mathew of Llandaff, Radir, C. This very ancient and long continuing family derived from Gwilyn, son of Gwaethfoed, Lord of Cardigan by Morfydd, dau. of Ynyr, King of Gwent, throught Gruffydd Gethin, ranked as tenth from Gwaethfoed, Ivan ap Gruffyd Gethin, who married Cecil, daug. and heiress of Watkin Llewelyn of Llandaff, of the lineage of Iestyn ap Gwrgant. He settled at Llandaff, his son, Mathew Ieuan Gruffydd, and his Grandson, David Mathew, introduced the surname which never ceased for twelve generations. They intermarried with the Flemings of Flemingston, Morgans of Tredegar, Gamages of Coity, Stradlings of St. Donats, and branched off at early periods into the vigorous families of Mathew of Castell Menych (Monk's Castle) and Mathew of Radir, Mathew of Aberaman and Mathew of Sweldom and Llancalach, all of whom are now extinct. The house of Llandaff supplied Sheriffs for Glamorgan in the years 1546, 1746 and member of Parliament in the person of Thomas Mathew, father and son in 1744, 1756. This same Thomas Mathew, Sen., of Llandaff, was Rear Admiral and Admiral of the White; and Thomas the son was a Major in the Army. In his election he polled 954 votes against 212 given for his opponent, Charles Van, Esq., By his wife, Anne, daughter of Robert Knight, Esq., of Sutturn, he had, besides several other children, a son, also named Thomas Mathew, Esq., of Llandaff. The Sheriff of 1769 who died 1771, s.p. the Mathews of Llandaff bore the arms of Gwaethfoed-or, a Lion rampany regardant sa. crowned GU).