What Grandad got up to in France 1939

I have just found a picture taken of a Hienkel HE111 shot down by my grandfathers anti aircraft battery in St. Asaph, France 1939. He was later transfered to Hong Kong where he was captured by the Japanese, then torpedoed by an American submarine USS Grouper while aboard the prison ship Lisbon Maru in 1942 on its way to Japan. 1,816 prisoners were aboard, and as a direct result of this action 820 were lost. Grandad was a good swimmer and made it to land, but was recaptured and spent the rest of the war as a Japanese prisoner of war. He refused to take any medals - and never spoke of his ordeal. He was a very quiet man, and died suddenly on valentines day dancing with Grandma. A great way to go for Grandad - not so good for Grandma!