My friend Tim Daly posted a pretty good write-up on the N series tractor evolution in October (see History). I disagree somewhat not considering Ferguson the inventor of the three point. I believe he should be considered so even though, as Tim notes, it was the others that really engineered the final product. Ferguson came up with the vision over a number of years and always had the final say on the design of that piece, just as many inventors do.
Apart from this I think a lot of Ferguson's contributions are overlooked by U.S. historians. Keep in mind it was he, helped largely by Roger Kyes, who joined the Ferguson company in 1939 from Empire Plow that established the entire dealer network that sold the tractors. A major one that probably saved the tractor was his intervention with Congress and the President of the United States in 1942 to obtain steel allotments for the 2N. Immediately after war was declared in December 1941,steel production was allocated away from the tractor production for all manufacturers-thus ending tractor production in any volume.
Henry Ford and Edsel had no interest in dealing with the government on this as they had bigger fish in retooling for tanks, jeeps and a factory for B24's in 1942. Ferguson was facing the end of his business and he and Kyes went to work. Kyes came up with eliminating the electrical system and also began searching the country for old Fordsons and second rate steel ingots from producers to melt down and use for the tractors. Harry Ferguson went right to the top first lobbying and then demonstrating the 9N to the Senate Investigative Commitee led by Harry Truman and Henry Wallace, then Vice President. Both were impressed and arrange a demonstration for FDR at Hyde Park. This was a real success as Ferguson put on his best to convinse the President of the benefit to mankind the tractor represented. Roosevelt was convinced and directed that the Ford tractors be allotted steel to maintain a high production for the duration of the war and he himself ordered one along with implements for use at his Hyde Park estate.
Without that action the 2N might well have passed into history in early 1942.