Walter d'Aincurt, the Domesday lord of Blankney. [Complete Peerage IV:118 note (c)]
-----------------------------------
Camden, in his "Britannia" (vol. 1, p. 559), after referring to this family as having flourished in a continued succession from the coming in of the Normans to the time of Henry VI and then to have failed for want of an heir male of William, 13th Lord d'Eyncourt, adds, "I was the more willing to take notice of this family that I might in some measure answer the desire of Edmund, Baron d'Eyncourt, who was so very earnest to preserve the memory of his name that, having no issue male, he petitioned King Edward II for liberty to make over his manors and arms to whomsoever he pleased; for he imagined that both his name and arms would go to the grave with him and was very solicitous to have them survive and be remembered. Yet this surname, for aught I can find, is now quite extinct and would have been forgotten for ever if the memory of it had not been preserved in books."
Camden does not quite correctly state the license. It is extant and may be found, printed at length, in Ryley's "Plac. Parl." (p. 547). It is dated 23 February 7th Edward II [1314], and enabled Edmund, Baron d'Eyncourt, as will be seen hereafter, to settle his lands upon his grandson William, 2nd son of his eldest son, John d'Eyncourt, in exclusion of Isabel, the female heir, she being the only child of Edmund, eldest son (then deceased) of the said John d'Eyncourt, which Isabel afterwards d. s. p.; and this leads us to trace the family of d'Eyncourt, who were formerly barons by tenure until summoned to parliament by writ, 22nd Edward I [1294].
Walter de Ayncourt, de Eyncourt, or d'Eyncourt, a noble Norman, one of the distinguished companions in arms of the Conqueror, was cousin to Remigius, bishop of Lincoln, who built the cathedral there, and obtained as his share of the spoil, sixty-seven lordships in several counties, of which many were in Lincolnshire, where Blankney was his chief seat, and the head of his feudal barony. By his wife, Matilda, he had two sons, William and Ralph. William, probably the eldest, while receiving his education in the Court of King William Rufus, d. there, as appears by an inscription on a plate of lead, found in the churchyard near the west door of Lincoln Cathedral, before Dugdale published his baronage, which contains an engraving of the plate, still preserved in the library of that church. From this inscription it seems he was descended from the royal family, probably through his mother. The inscription runs as follows: -- "Hic jacet Wilhelmus filius Walteri Aiencuriensis, consanguinei Remigii Episcopi Lincolnensis, qui hanc ecclesiam fecit -- Prúfatus Wilhelmus, regid stirpe progenitus, dum in curia Wilhelmi filii magni Regis Wilhelmi qui Angliam conquisivit aleretur III. Kalend. Novemb. obiit." [Sir Bernard Burke, Dormant, Abeyant, Forfeited and Extinct Peerages, Burke's Peerage, Ltd., London, England, 1883, p. 170, d'Eyncourt, Barons d'Eyncourt]