Post t-h tuning (was: The Crossover)

[John Walton]

Quoting from Andrew Higson:
> 
> It was not until the end of the 1920's that the current profile was 
standardised (after a 5-6 year cross over period) to accommodate the 
musical requirements of the carillon market. Ironic really when you 
consider how many ringing peals compared with carillons we make! Not 
that the current shape is bad, I hasten to add.
> 

This raises a question which I have wondered about for some time - 
since the principles seem to have been pretty much understood by the 
late 1920's, and some work from that era is regarded as amongst 
Taylor's finest, why is it that some later periods are less revered? 
Is it that they were again experimenting, in some new way, or was 
some of the knowledge temporarily lost?

The answers may be well known to the experts on this list, for which 
I apologise, but I await enlightenment!

John