[rsk289]

This may be a tricky one, as I'm talking UK market 289 here.
I have the correct early-style Lucas/Smiths ammeter for this car, which unlike the other instruments has a heavy bakelite casing and is a push-fit in the dash, with no provision for a retaining clamp or screws. It has a blue plastic window in the side but I can see no way of mounting or retaining a lamp for instrument illumination. Anybody know how this was done?
Same ammeter as used on the Ace.