He [William de Vernon] married Mabirie, or Mabel, daughter of Robert DE DUNSTANVILLE, 1st COUNT OF MEULAN of that family, by Maud, daughter and coheir of Reynold DE DUNSTANVILLE, EARL OF CORNWALL. She was living 1 May 1204. He died 8 or 10 September 1217, and was buried in Christ Church, Twynham [some say, at Tiverton]. [Complete Peerage IV:315-6, XIV:259, (transcribed by Dave Utzinger)]