As usuall , Ron from NSW is right. After making this post, I checked and found a plastic Japanese kitset which my wife purchased for me many years ago, clearly shows there were two construction options. One shows the fixed pitch option
or the three blade constant speed option. Even more startling is that it shows that the Spitfire had the markings of then Fl
Lt. Al Deere, a NZ pilot who flew the later model. It even had a miniature kiwi which could be affixed to the fuselage !
As a Cadet Pilot in the RNZAF in the early 50s one did not ask senior officers of their wartime role. I have since found that many kiwis , Australians, South Aficans, Canadians, Frenchmen, Polish and Americans served in the RAF, As the USA was not in the war until the end of 1941, how was it that Americans served in the RAF during the Battle of Britain in 1940?