I think both my grandfathers were too young, although my grand-uncle (grandfathers brother) might have been there, he was in the Royal Navy but I don't have a full list of the ships he served on and when. My great-grandfather avoided it too, he'd been taken out of the war by that point after his WWI injuries and the stress of being torpedoed by a uboat caught up with him. I don't know about my great-grandfather on the other side of the family. I must get back to ancestry.co.uk at some point and resume digging.