|SOME NOTES ON MEDIEVAL ENGLISH GENEALOGY|
Volume 5, page 176:
SIR WILLIAM BOURGHCHIER, or BOURGCHIER, [Count of Eu (d. 1420)] s. and h. of Sir William BOURGHCHIER (who d. in 1375) ... which last named William was a yr. br. of Bartholomew, LORD BOURGHCHIER.
As stated by Complete Peerage, vol.2, p.248 (Bourchier), the William who died in 1375 was in fact a younger son of Robert Bourchier (d.1349), and thus an uncle, not a brother, of Bartholomew.
The relationship is given in the Essex inquisition post mortem taken at Chelmsford 6 July 1433, after the death of Bartholomew Bourchier's daughter and heir Elizabeth, the widow of Sir Lewis Robessart. The jury found that Henry Bourchier, count of Eu, was Elizabeth's kinsman and next heir, viz. the son of William, the son of William, the brother of John, the father of Bartholomew, the father of the aforesaid Elizabeth [PRO C139/59/40].
[Tim Powys-Lybbe pointed out this error in February 2002. Thanks to Dave Utzinger and Brad Verity for further information.]