s. and h. of William Trelawny (d. bef. Mar. 1377), C49/14/9; Reg. Brantingham ed. Hingeston-Randolph, 49. by Joan, da. of Richard Doyngull. J.S. Vivian, Vis. Cornw., 475; Reg. Brantingham, 49. m. (1) by July 1393, Maud, da. of Robert Menwenick, JUST1/1502, rot. 189d; Reg. Stafford ed. Hingeston-Randolph, 287; Vivian, 475. 2s. Richard† and John II†, ?2da.; Trelawny’s daughters, Joan and Isabel, respectively married Thomas Upton of Trelaske and Stephen Trenewith† of Earth: Vivian, 475; The Commons 1386-1421, iv. 651; JUST1/1531, rot. 32; Plymouth and W. Devon RO, Yonge mss, 107/30, 37. (2) by Hil. 1425, CP40/656, rot. 106. Agnes, da. of Robert Tregodek of Tregodek. Vivian, 475; J.B. Rowe, Plympton, 232. ?1s. illegit. It is probable that John Trelawny of Plympton, Devon, ‘bastard’, who in 1431 clashed with the prominent Launceston burgess Simon Yurle*, was Sir John’s son: KB27/680, rots. 43, att. 1. Kntd. by Mar. 1417.