Job done. new bulbs from Europarts at 33p each and all is working fine (famous last words). I too lost my 10mm socket behind the trim Pegleg. That involved removing the plastic plate along the boot lip, removing the side pocket and pulling the trim out to retrieve it. At least that bit was pretty easy.
Those screws that hold the lamp cluster are mighty tight for the first 3 or 4 turns on the way out and on the way back in. Still, at least they are secure, I suppose.
All in all, a bit of a faff to change a stop and tail light.
B Max Titanium X 1.0 125 bhp in Magnetic with built in SatNav and rear sensors.