License plate light lens... how to replace?

This should be easy, but I haven’t yet figured out how to remove deteriorating license plate light lenses (I think I did it once years ago on an '84 XJS but that memory is gone). Cannot find mention of it in the volumes of XJS workshop manuals, nor on this website. Kirby’s book, and posts to this forum, discuss the lenses, but not the procedure to replace them.

Is it necessary to remove the entire reverse/license plate/decklid handle assembly from the decklid in order to replace the license plate lens? If so, can anyone describe that procedure?