Chesshyre was Secretary of the Order of the Garter from 1988 until 2003, having been trained for the role by his predecessor Walter Verco and by Verco's predecessor-but-one, Anthony Wagner. Upon his resignation Chesshyre had an audience with The Queen at Buckingham Palace, during which he surrendered his badge of office. Following the 1992 Windsor Castle fire Chesshyre was, together with Peter Begent, appointed heraldic consultant for the reconstruction of St George's Hall. Chesshyre was also Honorary Genealogist of The Society of the Friends of St George's and Descendants of the Knights of the Garter. He also served for twenty-three years as Honorary Genealogist to the Royal Victorian Order (1987–2010), again, succeeding Walter Verco. As Ulster King of Arms (merged with Norroy) Chesshyre also held the technically extant position of King of Arms, Registrar, and Knight Attendant of the Order of St Patrick. He was therefore briefly one of just two members of the Order of St Patrick, the other member being Queen Elizabeth II, who remains Sovereign of the Order.