My mother has just told me that she thinks my grandfather (fathers, father) served in the Navy during ww2
How can i find that out?

I have no idea if it's true or not. I do know that he was in the Merchant navy at one time.Unfortunately there is no one in my fathers family  alive to ask.
All i have to work with are my Granddads personal info,where/when born,marriage,parents etc

I had a look on the MOD site but the kinship form doesn't seem to apply to me,as i know nothing at all about where when he served.
Any advice would be greatly appreciated
Blue