The Pathfinder class grew out of the contest among torpedo boats, torpedo-boat destroyers, and the ships intended to defeat them. Armoured cruisers had once performed some of this work, but they could no longer keep up as destroyers became faster, especially after turbine machinery arrived. The Royal Navy needed a lighter cruiser able to screen, support, and lead its flotillas. Pathfinder combined cruiser endurance and command capacity with the speed needed to operate alongside destroyers.
Chapter · 6:36-8:12
Why the Royal Navy needed scout cruisers
The Pathfinder class emerged because older cruisers could no longer keep pace with the destroyers they were meant to support and counter.