Military Trench Watch Movement ID Help

Not sure if this is the correct section to post in but I am looking for help to identify the 13''' movement in a WW1 trench watch I purchased a little while ago. I posted on the Military Watch Resource and a member responded suggesting it is an FHF movement but I have no calibre number. I need a balance staff hence the question. Based on the diagram he sent and photos below I thought a 11244 or 1146 from what I have been able to find on the internet. Any help would be greatly appreciated.