The last major building site of Louis XIV, the Royal Chapel was completed at the end of his reign in 1710, and was designed by Jules Hardouin-Mansart in 1699, but died before the work was completed. The site was taken over by the architect Robert de Cotte (1656 - 1735), his student.
It was the latter who asked Grettepin, author of many sculptures that still adorn the Chapel, to create the key, the final version of which in gilded bronze was made by the founder Jacques Desjardins. Most of the decoration is concentrated on the ring: made up of two elegant scroll consoles framing an admirable motif with a royal figure formed by two intertwined Ls, which represents a true work of goldsmith's trade, it is surmounted by a royal crown with fleurs-de-lis.
It is likely that it has only been used on rare occasions, or even that its function has been purely symbolic.