What if the Indefatigable-class battlecruisers used the Lion-class gun layout while retaining twin 12-inch turrets?
Short answerThey would gain a much better broadside and likely become longer, with possible secondary gains in speed and armor.
NotesThe Lion-style centerline arrangement would give the ship a substantially better broadside than the historical wing-turret layout. Accommodating it would probably lengthen the hull. The panel suggests that the altered proportions might also permit a little more speed and somewhat better protection. Those improvements make a sounder ship, but the brief answer does not claim that they overturn the wider strategic course of the battlecruiser program.