File:Arms Grey of Merton, Norfolk, by Blomefield, 1806.png

Drawings illustrating the derivation of the arms of Grey of Merton, Norfolk. See text at File:St Peter's Church - south aisle east window - geograph.org.uk - 907109.jpg

Blomefield's text accompanying images, re the manor of Bunwell, Norfolk (Francis Blomefield, 'Hundred of Depwade: Bunwell', in An Essay Towards A Topographical History of the County of Norfolk: Volume 5 (London, 1806), pp. 136-7 [1]):

The ancient Baynards upon losing their barony of Baynard's castle, for rebellion against Henry I. had (Bunwell) given from them to the ancestors of the Fitz-Walters, as at vol. ii. p. 299 (re Merton, Norfolk). But this manor being granted to a younger branch before the forfeiture, it was never forfeited, though these Baynards bare their arms differing only in colour from the Fitz-Walters, their chief lords; as the Fitz-Walters did from the Clare family, whence they descended, from whose arms they only varied by a fess between two chevrons, instead of three chevrons born by the Earls of Clare, and in like manner the Cornherds or Cornerths, in imitation of the Baynards, their capital and chief lords, bare the same arms, only varied in colour, and often quartered them with the Baynards; but when Sir Thomas de Grey, Knt. married the heiress of Sir Richard de Cornherd, Knt. he laid aside the paternal coat of Grey, and he and all his descendants always used Cornherd's as their own, except Tho. de Grey, clerk, who always bare the ancient family arms of Grey, with a mullet; and when their son Tho. de Grey, Knt. married Isabel, daughter and coheiress of Fulk Baynard of Merton, the Greys ever since bare Bainard quartered with Cornerth.