Well said JiK...

"My dad learned in the 1920s - any such 'aids' then were not acceptable. You were expected to just 'learn'... :-)"

Another thing dredged up ... as a part of the one to one 'training', my dad's teacher would also play (occasionally, not the whole time!) and hold the perfect pitch and the student was expected to listen to the 'beats' and refine their position as their pitch got closer.