In reading Percival Marshall's book

Model sailing yachts, how to build, rig and sail them

which seems to be published in the 1930's, but after the Third Rule of 1934, [the book is free on Amazon], I came across Figure 33 which is entitled

Design for a 1-2/3":12" 6-meter yacht

.

It made me wonder who established this scale and when.

Basil

Take a look here

http://sixmetresailing.weebly.com/history.html

Also have a look at Grove pond Yachts Cliff Grove he has done some research into classic sixes and builds beautiful ones go through the suppliers page on the six metre website