The Didos carried torpedoes for their work with surface screening forces and also received ASDIC. That fit did not make them submarine hunters: the cruisers were not intended to detach and conduct offensive searches. The precaution reflected the Royal Navy's institutional memory of losing Aboukir, Cressy, and Hogue in a single day during the First World War. The equipment preserved defensive caution without changing the ship's primary tactical role.
Notable Point · 29:13-30:20
Why Didos carried ASDIC without becoming submarine hunters
ASDIC aboard the Didos reflected Royal Navy caution after the loss of Aboukir, Cressy, and Hogue, not an assignment to roam independently in search of submarines.