GWR serves a lot of Army areas, Westbury, Lympstone Commando, Basingstoke, Hereford etc, they always seemed like the most patriotic ToC to me so this suits them very well. They even have a dark green livery.
But principally the Navy, at Plymouth, who of course were at the forefront of the Falklands campaign. There has been a long tradition, back to steam days, of the rail staff at Plymouth being ex-Navy, across many departments, in a way you don't get elsewhere. The engineering staff at Laira commonly had this background of being from the engineering side of naval vessels, and elsewhere as well, the catering crews based there having had similar jobs serving as they were lurching along! To an extent this spread across the rest of the old GWR; when it was common to have done your time in the military there were a much higher proportion who had been at sea.
There used to be a trainee officers' initiative test where they were taken from the Navy college at Dartmouth in a sealed van somewhere (Brecon Beacons was popular), let out, no money, and told to find base and get back to it as quickly as possible. Getting a "lift" by train was the most common way. All the staff knew of this, and how to spot them in the shadows, and given their background there were very few who would put anything in their way. Not unknown for them to leave a can of tea somewhere close by ...
Does it still go on?