Three Incomparable-class battlecruisers after 1918

What happens if Britain ends the First World War with three operational Incomparable-class battlecruisers armed with 20-inch guns?

They overturn existing battle-line assumptions, destabilize the Washington Treaty, and push rivals toward faster ships, aviation, and new fire-control solutions because contemporary armour cannot answer them.

The scenario assumes that the enormous guns and turrets work, giving Britain weapons no contemporary battleship can reliably resist. The ships' 35-knot speed also makes the US standard battle line tactically obsolete because it cannot close or escape. Other navies would demand equivalent tonnage or a treaty specifically designed to stop further British construction, while Germany's treaty-limited 11-inch ships become even less credible. Designers might abandon the attempt to armour against a 20-inch shell and instead emphasize speed, fire control, or even layouts intended to let armour-piercing rounds pass through before fusing. The same pressure would accelerate naval aviation because aircraft could strike from beyond gun range, and an Incomparable-sized hull could support an exceptionally large carrier conversion. Four inches of deck protection gives the original ship some resistance to period bombs, but lifts and other openings remain vulnerabilities. The panel also imagines a second generation incorporating Queen Mary or Tiger design lessons at slightly lower speed, turning Fisher's concept into a sustained fast-capital-ship program.