As I thought John from the original description. Just double checking, as a number of replies were referencing the problems experienced with the (Land Rover) hydraulic switch.
Dave, tracing wiring can be a pain. As both brake lights are not working, at least you are looking at a common section of cable/interconnection. Good chance it may be under wheel arch rather than spare wheel space. Good luck with the search. If I was closer I'd offer an extra pair of paws/eyes, test meter &c.
D8921 L44FOR '93 4/4 Giallo Fly 2 seat
'90 LR 90 SW
'07 MINI Cooper