Chesshyre served for more than forty years as an officer of arms in ordinary to Queen Elizabeth II and as a member of Her Majesty's Household. He was Clarenceux King of Arms, the second most senior member of the College of Arms and the second most senior heraldic position in England, Wales, Northern Ireland, Australia, New Zealand, and several other Commonwealth countries. His other appointments included those of Registrar of the College of Arms, Secretary of the Order of the Garter, and Honorary Genealogist to the Royal Victorian Order. Chesshyre undertook heraldic and genealogical work for high-profile clients such as the former prime minister Sir Edward Heath. He wrote seven books, including the official history of the Order of the Garter.