A 1920s fleet still needs a 1940s modernisation

What if the Royal Navy had scrapped its old fleet and rebuilt it in the late 1920s?

It could have produced an interesting force, but it would still need substantial modernisation by the 1940s because naval warfare had changed again.

An earlier construction programme would not provide a permanent solution. A radical late-1920s rebuild would be expensive and would optimise the fleet for assumptions made before the next decade's changes were visible. Naval warfare, sensors, weapons, and operating demands evolved enough that even a well-focused 1920s force would need serious updating for a 1940s war. The counterfactual shifts the modernisation burden rather than eliminating it.