Faster R-class battleships with small-tube boilers

How would R-class careers change if the ships had small-tube boilers?

At roughly 28 knots they would become useful fast battleships, but Britain first needed an industrial base able to build reliable boilers at that scale.

The counterfactual begins with the Queen Elizabeth class adopting small-tube boilers, making the same machinery choice plausible for the later R class. Around 28 knots would make both classes far more useful in fast operations and reduce pressure on Hood, Renown, Repulse and Prince of Wales. Admiral Somerville's choices during Operation C would also improve because more of his battleships could keep pace with carriers and cruisers. The machinery gained efficiency from greater heating surface and, in later development, higher pressure. The obstacle was industrial: most British yards were not ready to supply reliable small-tube units at battleship scale, so adopting them would concentrate orders with the few capable makers.