Leo's great web site here
http://www.genealogics.org/getperson.php?personID=I00108554&tree=LEO
gives Maud as a daughter to Sir Thomas Grey and Joan de Mowbray, that is,
one generation earlier. This chronology works. Leo cites Living Decendents Vol
III as his source so I'm assuming they corrected this Volume II error in the
next volume, that is in Volume III as Leo cites.
Will Johnson
Walter Lee Sheppard, Jr., after reviewing various commentaries pro and con,
had assigned Maud Gray (wife of Robert Ogle) as daughter of Sir Thomas Gray
and Alice Neville in his article "The Wetherill-Watson Royal Ancestry", New
England Historical and Genealogical Register, vol. 104, 1950. But he
submitted a note a half a year later (vol. 105, 1951, p. 155) saying that
Donald Lines Jacobus had called his attention to a chronological problem
with this parentage and that the identification of Maud Gray as a daughter
of Sir Thomas Gray and Joan de Mowbray "must be accepted in its stead."
-- Don Stone