The Z/Ca-classes were the first of Britain's War Emergency Programme utility destroyers (known as the 10th and 11th Flotillas respectively) to be fitted with the 4.5-in QF Mk. IV gun. Despite its smaller caliber compared to the 4.7-in guns of the previous flotillas, the QF Mk. IV carried a heavier shell and with a maximum elevation of 55 degrees was a more effective dual-purpose weapon. Wartime anti-aircraft armament varied among the ships but usually composed of a twin Bofors mount, and various combinations of 2-pdr and 20-mm guns. As many as 130 depth charges could be carried in addition to a pair of quadruple torpedo tubes. Aside from that, there was little structural difference from the preceding classes. The Z/Ca-class was notable for being the first class of British destroyers to not suffer a single loss in combat during World War II, although by the time they were commissioned (from mid-1944 onward), conditions were far less hostile for the Allied navies. Consequently, the Ca flotilla was modernized post-war as general-purpose escorts with improved fire control, a pair of Squid ASW mortars (which replaced the torpedoes) and twin Mk. 5 Bofors guns. Two of the ships (HMS Caprice and HMS Cavalier) also received Seacat GWS20 anti-air missiles. Four of the Z-class ships were sold after the war to Egypt and Israel where two were lost in combat (the only war losses of the class); the remainder were paid off and scrapped after war or in the 1950s except for HMS Zest which was converted to a Type 15 frigate. The Ca-class served for longer, being paid off in the 1960s although the two Seacat-armed ships remained in service until the early 1970s, making them among the Royal Navy's longest-lasting wartime ships.

Most of the ships in these two flotillas served as Arctic convoy escorts in the final months of the war. After VE-Day, they were used in support of the re-occupation of former German-controlled countries and as guardships. The Z-class had the shortest careers, as most were decommissioned within a decade after the war, but two were sold to Israel and another two to Egypt. Of these, Eliath (formerly HMS Zealous) was sunk shortly after the Six-Day War by SS-N-2 Styx missiles fired from an Egyptian missile boat. Three years later, in 1970, the Egyptian El Qaher (formerly HMS Myngs) was sunk by Israeli aircraft. A few of the Ca-class ships served with the British Pacific Fleet and all had much longer post-war service. HMS Cavalier is the only surviving ship and is preserved at Chatham.