Person:Isabel De Mohun (2)

http://www.medievalgenealogy.org.uk/cp/p_willoughbydeeresby.shtml#p658

Volume 12, part 2, page 658:
He [Robert de Willoughby (d. 1317)] m., in or before 1303, Margaret, da. of Sir Edmund (DEINCOURT), 1st LORD DEINCOURT, by Isabel, da. of Sir Reynold DE MOHUN, of Dunster, Somerset.

According to Complete Peerage, vol.4, p.120, Isabel, the wife of Sir Edmund Deincourt, was the daughter of Sir Reynold Mohun by his wife Isabel, daughter of William (de Ferrers), earl of Derby. But the issue of Isabel de Ferrers had certainly failed by April 1327, when an inquisition was taken after the death of John Meriet, who had married her granddaughter. At this time Margaret was still living. Clearly, either she was the daughter of another wife of Edmund Deincourt, or Edmund's wife Isabel was not the daughter of Isabel de Ferrers.

http://www.medievalgenealogy.org.uk/cp/p_deincourt.shtml

Volume 4, page 120:
He [Sir Edmund Deincourt, Lord Deincourt (d. 1326/7)] m. Isabel, da. of Sir Reynold DE MOHUN, of Dunster, Somerset,(b) by his 2nd wife, Isabel, da. of William (DE FERRERS), EARL OF DERBY.(b)
Note b:
Extracts, by St. George, from the Mohun Cartulary, f. 37v.

The issue of Isabel de Ferrers had certainly failed by April 1327, when an inquisition was taken after the death of John Meriet, who had married her granddaughter. But at this time at least two of Edmund's children were alive or had surviving issue (his son John and his daughter Margaret - see Willoughby, volume 12, part 2, page 658 [Citation S1]). Clearly, either his wife Isabel was not the daughter of Isabel de Ferrers, or he had another wife who was the mother of these children.

[Peter Stewart pointed out this contradiction in May 2001. The problem was also discussed in January 2002 by Douglas Richardson, Cris Nash and Rosie Bevan.]