I think that the English way of measuring up for the "correct" size if frame ie taking 9" off the inside leg measurement with the rider in stocking feet, always ended up with a frame too large Didn't the Italian CONI regulations suggest taking the same measurement and reducing that by 10" or thereabouts?
Some years ago, probably late 80s early 90s I read an article in the French magazine "Velo" or "Le Cycle," about the methods used by Dr Andre Almel(?) an adviser the the French Federation and to riders such as Hinault and Fignon. His basis for calculating a rider's correct frame size was to take the inside leg measurement as above and multiply by 67% - a formula which in my case would produce a frame-size very similar to that obtained by knocking off 11"
I used to ride 21.5 or maximum 22" but now ride frames between 49cms and 51 cms. The top-tube seems a heck of a long way down!
Norris Lockley