FYI: The first designs of what became the Spitfire were floatplanes designed for air racing in the Schneider Trophy competition. From 1927-37, the Submarine Aircraft Company designer, R J Mitchell, worked to create smooth airflow over ever thinner wings for greater speed. Following his death in 1937, his design was still the starting point for the successive models/marks.
I believe that the early Spitfire Marks had hand-cranked landing gear like many of its contemporaries, now that is a task to build the arms!
Later models had extended ranges and different armament. Almost everybody except the US went for cannons over machine-guns (except for P39) while the US saw 50cal as best for larger capacity. Don’t know if there was ever a study on that decision post-war.
Ah yes, I was aware of that - and that's one of the sketches the actor playing Mitchell shows in the video.
Hand cranked landing gear indeed. Robert-Stanford Tuck's 'Fly for you Life' mentions that when he was testing Spits back in the 1930s - how difficult it was to maintain a smooth climb while pumping the undercart up.