Why British medium AA guns resisted standardization

Why was medium anti-aircraft gun standardization not a high British priority before the 1950s?

The navy had a vast existing force and supply system to support, making rapid standardization expensive and disruptive.

Britain had a very large navy to support before the 1950s. That existing commitment is the explanation given for the low priority attached to standardising medium anti-aircraft guns. The answer does not identify a particular calibre or replacement programme.