Apologies as it took me a while to find the emails. I used J E Allnutt & Sons which was a recommendation from Olivier Chambert (.olli.) in 2020 for a service on this. I seem to remember the cost being just over £300 and these were the instructions
1. Mechanical service including some attention to winding stem.
2. New crystal
3. Hands re-lumed to match existing.
4. Nothing to dial but would appreciate an opinion on whether something more needs to be done to stabilise chip at 1.
5. Very light polish to case with rouge clothe – no refinishing.
I didn't ask them to remove the lume and they didn't seem to be overly fussed about the presence of what I assume is radium. I've been in contact with James Hyman recently about another project and he didn't want to do it without the lume removed first - with yours I'd be inclined to leave it alone as much as possible.
I also had another look at my Omega and took some photos. I should begin by saying that I put the watch into the wristlet so no assumption about it being a trench watch should be made - it's a small lady's pocket watch.
Movement number 4528566 which puts it between 1912 and 1916.
Case number 5291038 which puts it between 1915 and 1923.
We can probably assume the case hallmarks give us more information. Stamped in London and bearing the t of 1914/15. Imported by Selling Agency, a subsidiary of Dimier Brothers and the Omega agents at the time
Do you think it's the same movement or rather a variation of the same?