pg 52, Burke's " A Genealogical History of the Dormant, Abeyant, Forfeited and Extinct Peerages of the British Empire" published 1883
"A History of Northumberland Part II Vol II" by Rev. John Hodgson, published Newcastle 1832: The Barony of Mitford extended over the whole of the parishes of Mitford, Meldon, Ponteland, and Felton, in this county, and of Greatham, in the county of Durham, and with the exception of such parts of it as were given in free alms to the clergy of its several parishes, and to monasteries and hospitals, continued in the possession of the ancient family of Bertram, unincumbered and entire, till the death of of Roger Bertram the Second in 1242. Tradition holds her dim torch over it into times prior to the conquest: the steady rays of history do not begin to beam upon it till the reign of Henry the Second (1154-89). John, lord of Mitford, had an only daughter, Sigil or Sybil, whom the Conqueror married to sir Richard Bertram, a son of the lord of Dignam, in Normandy. This Sigil is said to have had an uncle, Matthew de Mitford, from whom the families of Mitford, of Mitford and Exbury, and of Baron Redesdale, of Redesdale, derive their descent.