A British carrier force could change Halsey's Leyte Gulf choice

If British carriers were present at Leyte Gulf, would they follow Halsey north?

Probably not. Halsey could leave them to cover the battle, placing Philip Vian's carriers against the Japanese force around Yamato.

In this counterfactual, William Halsey detaches the British force as cover while taking the American fast carriers north to hunt the Japanese fleet. That gives him an additional force to leave behind instead of requiring every available carrier to follow. British carriers under Philip Vian would then face the Japanese force built around Yamato. An aggressive Royal Navy response could have the carriers close rather than withdraw and inflict heavier Japanese losses. One additional allied formation could change an admiral's operational options at a decisive moment.