The Danaes were based on the design of the preceding C class series, but were lengthened by 20 feet (6 m) to allow a sixth 6-inch (152 mm) gun to be worked in between the bridge and the fore funnel.

However, Danae, Dauntless and Dragon were ordered before the Capetown group, and therefore did not incorporate the improved bow design of the latter; the C class were very wet forwards, and in the Capetowns sheer was increased forwards into a knuckled "trawler bow".

Such was the success of the knuckled bow that it was incorporated into all subsequent British cruisers (except Birmingham of 1935 which was completed without).

Delhi, Dunedin, Durban, Despatch and Diomede were provided with flying-off platforms for a wheeled aircraft aft.

All aircraft equipment were removed and Dragon and Dauntless had their bridges rebuilt along the lines of the rest of the class.