The office of Garter King of Arms, of which Gwynn-Jones was the 36th holder, was created by Henry V in 1417, initially concerned with the ceremonies of the Order of the Garter. While still performing these, Garter is also in charge of Royal heraldry and the arms of peers, as well as exercising a supervisory role over the English heralds.
Gwynn-Jones was a familiar face in the House of Lords, where he was responsible for introducing new peers to their seats.
In 1967, after writing to the College of Arms offering his skills in history and genealogy, he was employed as assistant to Colin Cole, then Windsor Herald. He became Bluemantle Pursuivant in 1973, and was promoted to Lancaster Herald in 1982. He was appointed by The Queen to the position of Garter in 1995 following the retirement of Sir Conrad Swan.
Gwynn-Jones was was Secretary of the Harleian Society from 1981 until 1994, Inspector of Regimental Colours from 2 October 1995, and Inspector of Royal Air Force Badges from 1996. He was also appointed in 1995 Genealogist to the Order of the Bath, Genealogist of the Order of St Michael and St George, and Genealogist of the Most Venerable Order of the Hospital of Saint John of Jerusalem. He was non-executive Vice-President of The Heraldry Society from 1996.
Gwynn-Jones was appointed Lieutenant of the Royal Victorian Order in 1994, promoted Commander of the Royal Victorian Order in 1998, and appointed Knight of Justice of the Most Venerable Order of the Hospital of Saint John of Jerusalem in 1995. In anticipation of his retirement HM The Queen promoted Gwynn-Jones Knight Commander of the Royal Victorian Order in the 2010 New Year Honours.
You can read more in the Telegraph Obituaries at http://www.telegraph.co.uk/news/obituaries/7975958/Sir-Peter-Gwynn-Jones.html