I had been wondering how my grandfather managed to avoid active service during the Great War without collecting a pillow full of white feathers- and then I found this picture of him bending over a drawing board with "Vickers 1916" written on the back.
So that's the answer. He was working or serving an apprenticeship at Vickers- the arms manufacturer- and that would have counted as war work and exempted him from conscription.
Forward a generation. My grandfather tried to swing my father a commission in a "good" regiment but failed (we have the correspondence somewhere) and he (my father) ended up in the Navy.
So far as I know he never went to sea but, having trained as an engineer, served in a bomb disposal unit based, for at least part of the war, on Romney Marsh. I was digging around a few weeks back and came up this which- I think- shows him at work. A hole has been dug in a flat landscape which is almost certainly Romney Marsh, there are pipes in place which will be for pumping water out of the hole and at the bottom of the hole will be something the Germans dropped. I think my father is the man in the peaked cap in the middle distance.