Seventeen N3 battleships anchor Britain's 1939 battle line

What if every British battleship and battlecruiser became a fresh N3-class battleship in 1939?

Britain gains about seventeen slow but exceptionally powerful 18-inch battleships while the new KGVs provide speed.

The N3 transformation would reduce the speed of Britain's fast capital ships to roughly 23 knots. In exchange, the fleet receives heavy protection and 18-inch guns that would make these ships difficult opponents. The count reaches seventeen by including the two Nelsons, three battlecruisers, five Revenges, five Queen Elizabeths, and the surviving auxiliary battleships Centurion and Iron Duke. The scenario is interpreted as beginning on 1 January 1939, before any King George V-class ship has launched. Those vessels therefore remain unchanged on the slips and become the faster part of the future battle fleet.