Archbishop Walter is *not* one of the Codnor Greys! It appears to have been his *mother* Hawise who was the de Grey - unless she married a de Grey cousin - and in any case she was the more important figure.
Hawise was the sister of John de Grey, Bishop of Norwich, and her sons were Sir Robert de Grey (later "of Rotherfield") and the aforementioned Walter. We have all this in her own words: "Hawisia de Grey vidua, pro animabus omnium antecessorum et consanguineorum, et precipue pro anima Johannis de Grey fratris mei quondam Norwicensis Episcopi, assensu Dni. Roberti de Grey filij et heredis mei, concessi et quantum ad patronam pertinet dedi Deo et Sce. Marie de Oseney et canonicis ibidem Deo servientibus ecclesiam de Cornewell ad donationem meam pertinentem in puram et perpetuam eleemosinam. Testibus Dno. Waltero de Grey, Wygorniensi Episcopus filio meo, &c.' " [Blomefield, Norfok I:478, cites 'Mss. penes P. L. Norroy, p. 15, excerpt. e Cartis per Ric. St. George.']
Translation: Hawise de Grey widow, for the souls of all my ancestors and relatives, and [especially?] for the soul of John de Grey my brother, former Bishop of Norwich, with the assent of Sir Robert de Grey my son and heir, give and donate [specified property to specified religious organizations - the Latin is a little dense here]. In witness [Right Reverend] Walter de Grey, Bishop of Worcester, my son.
The charter dates fairly precisely to 1215 - her brother John is deceased, but her son Walter is not yet Archbishop of York.
Here is Hawise, her brother, and her sons: Hawise de Grey
John de Grey, Bishop of Norwich
Sir Robert de Grey, of Rotherfield
Walter de Grey, Archbishop of York
Their place in the Grey family thicket is conjectural and frequently disrupted by Bad-Merges.
And sure enough, here we go again, with another male chauvinist "authority" giving his *opinion* that Archbishop Walter "was so" a Codnor Grey: Walter de Grey, NOT Archbishop of York
But that is precisely who he *could not possibly* have been. His mother's name was Hawise de Grey, *not* Isolda anybody. See above.
Even this early on, the Grey family had split into several branches, and the Archbishop *did not* belong to the Codnor branch, period end of sentence.
Just because something is found in a book, even an "authoritative" book, does not make it true.
There may have been a Walter in the Codnor crowd - it was a rather popular name - but he *was not* the Archbishop of York.
https://fmg.ac/Projects/MedLands/ENGLISHNOBILITYMEDIEVAL3D-K.htm#_T... - Cawey can't quite commit to the thesis that Hawise was the de Grey because linguistic reasons, but he gave enough info that I was able to track down the original charter. It's pretty explicit.