I stumbled across this 1930 Lachenal Price list that adds new complexity to the concept of Old Pitch :
(Collected by Chris Algar) on Concertina.com -Posted 07 March 2005.
"Lachenal & Co. list of models and prices for English, Duet, and Anglo concertinas. Dated c. 1930 by internal evidence".
In the price list, Lachenal offers the following tunings:
Old Philharmonic...........C=540 vibrations
Society of Arts..............C=530 "
New Philharmonic.........C=532 "
Normal............................C=517-520 "
"Customers are requested to kindly to state pitch required when ordering"
Thanks to Chris for his amazing contributions to such history!