Fishing with the reel down was first used by tournament casters in conjunction with a longer rod in order to generate more tip speed. Neil Mackellow switched to this setup in order to be able to compete with Paul Kerry (who has always used the reel up position).
Sorry to disagree on your timing...Low reel was in use 100 years ago, I have a cane two-piece that belonged to Frederick Aflalo, the Mike Millman of the late 19th and early 20th century, with a low reel fitting, I was taught what is now referred to as the pendulum cast by Dennis Darkin in 1971/2, along with the late John Darling, and he used his own home-made reels, including a lever-drag model, in the low position on a Davenport & Fordham "Super Surflite", fitted with a sliding reel fitting that was designed by Dennis for that rod. The rod was 11'4" long.
I later bought the same rod that Nigel Forrest was using, the ABU 464, 11'6" long, that he used to set several records in that era. He used it reel down, I tried low reel and found it easier than it looked, and have used it ever since for long-range work. In those early years, we didn't really understand what happened and why. Today, the application of a little logic and simple science makes that understanding relatively easy.
philtherod