A musician friend said to me today that he thought A-440 Pitch - ie. Concert Pitch or Modern Pitch was not adopted until the 1920's or 30's.

Now may question is -
If it was adopted AFTER 1915, where does that put the songs and tunes collected BEFORE that time. ie. how does it affect the keys, etc.
This is a follow-on to the thread - Does the Key make a Difference?

Tim Radford