Dido-class firepower left little modernization margin

Why did the Dido-class cruisers have limited postwar longevity?

They packed their firepower into a very small wartime hull, leaving little space or weight margin for later additions.

The Didos were unusually small cruisers built around a concentrated armament. Their design asked how little ship could carry the required firepower, leaving limited room for additional systems. That tight fit made later modernization difficult and helps explain the class's limited postwar longevity. The comparison with Colony-class ships places both types within wartime pressure to compress capability into economical hulls.