Seen on a stock buckle with a London Lion Passant Guardant of 1740 -1756 period.
Mark somewhat similar to William Gould's largeworker mark of 1748 (Grimwade 3135, but certainly not a match ) but unlikely to be another of his marks.
Only suspect is William Garrard. Although all his marks were registered are as largeworker, he appears in the PR1773 as a haftmaker. Often bucklemakers, especially in the late 18th century , also made sword fittings etc.
If the mark is WC - many possibilities !