Looks as if it could be a GE 160W EZ-Merc self ballasted lamp, but not sure. If not that then maybe a GE 100W mercury lamp of some description..? Ok, you got me, what is it..?

It does have a very soft warm tone but wonder if I can see a start resistor of a mercury lamp hanging down.

So, it is a 100 W mercury lamp indeed (not self ballasted), but not from GE. Any idea about the make and type exactly? Not many mercs were capable of such nice warm white light

Westinghouse A23 100w /n lamp?

Exactly, it's a 100 W Westinghouse Styletone, the most elaborate warm-white mercury lamp ever made! It has three materials deposited onto its bulb: yttrium phosphovanadate and magnesium fluorogermanate phosphors, the latter acting also as a blue-light filter, and silica nanoparticulates as a precoat, working as a short-wavelength optical reflector.

The resulting light color is truly excellent, you wouldn't know that this is a mercury lamp, but the lumen output is a bit on the low side however (3600 lm, initial) - still much higher than that of a softone 100 W incandescent lamp though (1300-1700 lm).

I knew what this was as soon as I saw it!

Especially since this came from you

Ah, thinking about it, I did realise it might be one of those, I think we had one from you as well, Eric..? The brain cell is a bit hazy right now, still getting over Sammi being in hospital

Edit 28/03/25 - Found a photo of the one we have, see here)