New boilers could preserve a rebuilt Queen Elizabeth's speed

Could a 1930s modernization of the ten-gun Queen Elizabeth concept retain its 28-knot speed?

Yes. More powerful modern boilers could deliver the same speed with fewer units and less machinery weight.

A 1930s rebuild could exploit newer boilers with more power per unit. Fewer boilers would reduce machinery weight while preserving about 28 knots. That margin matters for the ten-gun counterfactual because the design already carries a heavy battery and protection scheme. The estimate applies to a hypothetical modernization rather than the historical class as completed.