All Government Military records are located at the NARA and may be in microfilm form. So try www.archives.gov and search. Also http://aad.archives.gov/aad/http://aad.archives.gov/aad/for some online databases but I really don't think they will be much help without a name. If the father was Navy and ashore and provided "stores" then it sounds to me like he was in the Supply Corp, (a storekeeper) (like my dad was in the Korean War) or if by chance not Navy but Army then in the Quartermaster Corp (a Quartermaster).
Have you tried the family that had the wedding to see if any photos exist of the guests of the wedding. Surely someone that that provided the food or "stores" has a photo taken with family. Was there a guest register? Have you looked for any local sources of wedding announcements or newspaper item about the wedding that many have listed the names of the guests that attended? Did the couple married have any children? Could be they were told the story of their parents wedding and maybe the name of the generous American that helped out.
Cornwall has a Maritime museum that may have WWII information such as ships docked or units there.
Try Google Books and search to look for a book that may have been written about the place or being stationed in the area during WWII.