Just an update to the watch posted by Ash above, which he has kindly let me have and which I took to Simon at STS yesterday for a service.
It's a 105002-62, 19833074, and Simon reckoned it had not been opened or touched since first purchased. This argues against grey dials being later service replacements and Simon considered that damage to the dial would have occurred under the glass.
The pictures (taken by Simon) don't do justice to the satin finish which is quite beautiful. The damage to the paint surface is particularly areas around the dial step and rims of the sub-registers and there are patches of rust adjacent to some of the lume plots that I had initially thought were smudged luminous material. But the overall appearance pleases me.
I have asked Simon to polish the crystal, service the movement and do nothing else. I'll post the "after" pictures in 8 to 12 weeks when he has worked his magic.