The counterfactual helps explain the priorities of the ships Britain actually built. Nelson and Rodney would be the fleet's only 16-inch-gun battleships, carrying the maximum calibre permitted by the Washington treaty and considerable status as a result. Because there were only two costly hulls, losing either would remove half of this capability, making protection and survivability more valuable than pushing for 28 knots. A two-ship fast squadron would also be small enough for rival navies to design around, whereas five or six common-speed ships could reshape the whole balance of the battle line. Their unusual armour and layout follow from that fleet policy and the risks of concentrating the capability in two hulls.
Notable Point · 44:21-45:45
Why treaty-maximum guns made the pair precious
As Britain's only treaty-maximum 16-inch-gun battleships, Nelson and Rodney had to emphasize survivability over the speed that a larger class could exploit.