[Bell Historians] Trebles on higher numbers

[Andrew Aspland]

"Two bells of the same pitch but different thickness will have different
external profiles but the same internal profiles, because it is
internal diameter which controls pitch."

Is this statement actually correct? Surely the thicker bell will have a
higher pitch and when it is tuned down on the inside it will end up with a
bigger internal diameter than the other. To take an extreme case a handbell
of the same pitch as a tower bell does not have the same internal diameter.

Andrew