The archives of the Abbey-Principality contain this interesting paper on how knights are created, and indeed how they may style themselves, by the late Professor Vincent Powell-Smith (1934-97).
Powell-Smith, a barrister who held numerous academic positions in law, came under the mentorship of the Most Revd. J.E. Bazille-Corbin (q.v.) while exploring his religious vocation, and through his influence became a member of a number of chivalric bodies. He was appointed an Officier in the Order of the Crown of Thorns, but withdrew from the Order in June 1962.