This is also the proportions in the 60th edition; but the 20th goes with 1/4-1/4 sweet/dry; 1 1/2 gin; 1/2 tsp lemon-curaçao; 1 dash bitters. Wonder when between 1961 and 1979 the change happened?
That is very interesting. Now all we need is others who have editions between the 20th and the 60th to tell us what their edition says and thereby work out when it evolved to, in my opinion, the more balanced version.