L. Roucel became a master by privilge in 1763, meaning that he was not required to satisfy the normal rules of the guild, but, according to Seelig, he was sponsored by Alexis Porcher. It is clear that he worked in the premises of Jean Ducrollay (q.v.) as early as 29 July 1756 as a box struck with Ducrollay's mark and the Paris marks for 1755-56 is signed and dated by him. It is further engraved with the name of the supplier “Jacmin Joyallier du Roy A Paris”. The box was made for King José I of Portugual and is now in the Ajuda Palace, Lisbon. He was still lodging with Ducrollay in 1759 but by 1764 he advertised himself as royal goldsmith from the quai de l'Horloge at the sign of the Plump Grape (Gros Raisin). Two years later he had moved to the quai des Morfondus. However when he advertised the loss of a snuffbox in tortoiseshell, mounted in gold, with a miniature on the cover showing a nun in a chemist's shop, he gave his address as the quai de l'Horloge again. By 1776 he appears to have moved back to the quai de Morfondus but these changes of address might have been caused by the re-classifying of the street rather than by a physical move. He died on 6 March 1787. His work was much sought after in the nineteenth century as frequently he had his name inscribed on boxes and was therefore easy to identify as a maker.