Because the Nazis dressed better than the Brits. Seriously though, I had two uncles who fought in the Battle of Britain.
Born in Tipperary , they emigrated to England and joined the RAF. One was shot down over France , but survived the war . The other survived it as well.
The first job that I had at 16 was working for a painter who had fought after landing on Sword beach. He told me that he had shot a Hitler youth , who was only 16.
He was a nice man . Fifty thousand Irishmen fought for the Allies in WW2, and many never returned. They signed up without even thinking about it.