What difference would a third Renown-class battlecruiser make?
Short answerIt could provide another modernized fast capital ship, strengthen treaty-era fleet numbers, and materially improve wartime raider-hunting groups.
NotesA third ship, possibly named Resistance, could survive treaty negotiations alongside Renown, Repulse, Hood, the Queen Elizabeths, and the Nelsons. If modernized on Renown's timetable, it could double the fast 15-inch-gun strength available for operations such as hunting Scharnhorst and Gneisenau. More heavy shells on target increase the chance of slowing one raider. Destroyers could then finish the damaged ship while the remaining capital ships continue the pursuit.