|SOME NOTES ON MEDIEVAL ENGLISH GENEALOGY|
Volume 2, page 242:
He [William (de Botreaux), Lord Botreaux (d. 1462)] m., 2ndly, before 1458, Margaret, da. of Thomas, LORD ROS,(e) by Eleanor, da. of Richard (BEAUCHAMP), EARL OF WARWICK ... His widow m., between May 1462 and 1464, Thomas, LORD BURGH, who d. 18 Mar. 1495/6, and was bur. at Gainsborough. She d. 1488, and was bur. there. Inq. p. m. 26 June (1489) 4 Hen. VII.
Early Chan. Proc., bundle 26, no. 461, dated 1404-1426 and 1456-60, shows that Sir William Botreaux was then m. to Margaret, da. of Thomas, Lord Ros (d. 1383).
The Margaret Ros who married Thomas, Lord Burgh, was certainly the daughter of Thomas, 8th Lord Ros (d. 1430) by his wife Eleanor Beaufort. The account above asserts that the same Margaret married previously William de Botreaux, although the footnote appears to imply that William's wife was the daughter of Thomas, 4th Lord Ros, who died in 1384 (that is, the grandfather of the Thomas Ros who married Eleanor Beaufort). Note that a daughter of the 8th Lord Ros could not have been born before about 1425, whereas William Botreaux was born in 1388/9, so this would make her at least 35 years his junior.
[This problem was also discussed by Douglas Richardson and John P. Ravilious.]