This is the kit of parts that I have, now that I have stripped a Lucas red spot ammeter that I bought on eBay from a member of the AOMCC, for a lot less than one can spend on such things.
It is a bit of an oddity. It seems genuine, it has a Lucas part number and is made of parts of approriate 'quality'. It is marked '1980', and I guess it was a replacement part for vehicles still using red spot ammeters. It is marked 'Lucas' on the dial, but it does not have a window in the back, like the earlier versions that would have graced Amelia's curves when she was new, and it has no facilities for an ignition lamp internally so it could not have functioned as the red spot ammeters were intended to do.
The plan is to replicate the parts used for the ignition lamp and to cut the window through the ammeter, so that we end up with a suitable white faced ammeter with the functionality that we need.
Here's are the prototype parts for the ignition lamp. Following the style of the original ammeters, I have used a plastic card to replicate the tufnol insulator that is used to mount the lamp holder, just to get the shape, and the position of the lamp correct in relation to the aperture on the back of the meter.
The lamp holder is mounted on a small piece of 0.5 mm aluminium sheet, pop riveted to the insulator. There is a plastic insulator between the centre terminal of the bulb holder and the mounting bracket.
So for now, the lamp is in the correct place. We will reassemble and see if it looks OK from the front, when it is illuminated, then we will make some nicer parts.
And here it is with the ignition lamp on! Isn't it exciting!