He [William de Kerdeston] married, 1stly, before (probably two or three years before) 9 February 1325/6, Margaret, daughter and heir of Sir Edmund BACON, of Ewelme, &c., by his 1st wife, Joan DE BREWES. She appears to have died in 1328. [Complete Peerage VII:191-3, XIV:409, (transcribed by Dave Utzinger)]
Note: CP uses Joan de Brewes married name in the above article. She was really Joan Beaumont, widow of Giles de Brewes.