Armament
The class were intended to be armed with ten 5.25 inch (133 mm) guns in five twin turrets, which were of the same circular design as the secondary armament in the King George V-class battleships. A shortage of the guns, due to difficulties in manufacturing them, led to the first group being armed with only eight 5.25 inch guns in four twin turrets. The fifth twin turret was added later to Dido only. The first group was also armed with a 4 inch (102 mm) gun and two quadruple QF 2 pounder (40 mm) "pom-poms".
The second group had the five twin 5.25 inch guns but did not have the 4 in (102 mm) gun. The third group's armament was changed due to the shortage of 5.25 in guns, being armed with eight 4.5 inch (113 mm) guns in four twin turrets instead. The 4.5 inch gun was better suited to the primary anti-aircraft role of the Dido class. The 4.0 inch (102 mm) gun was also fitted and its 2 pounder armament was increased from eight to ten.
The Bellona sub-class differed in appearance somewhat from their predecessors. They had eight 5.25 inch (133 mm) RP10MkII guns in four twin turrets and had vastly improved anti-aircraft armament, with twelve 2 pounder guns and twelve Oerlikon 20 mm cannons. The bridge of the Bellona-class was lowered by one deck compared to the previous three groups, which allowed full radar control to be fitted to the 5.25 inch (133 mm) turrets and 2 pounders, due to the decreased topweight. These ships used the HACS high angle fire control system. The two funnels were more upright than the raked ones of the original Dido-class.
Read more about this topic: Dido Class Cruiser