One of the ships, "Exmouth", was later converted 1966–1968 to act as experimental trials vessel for gas turbine propulsion, becoming the first major warship of the Royal Navy to be entirely powered by gas turbines. In this configuration she was easily distinguishable from other members of the class due to her larger (non-cylindrical, streamlined) funnel and large air intakes sited immediately fore and aft of the funnel. The success of these trials led to the adoption of all-gas turbine propulsion as standard on subsequent Royal Navy warship designs (Type 21 & 22 Frigates, Type 42 destroyers, 'Invincible' class carriers).