Could Nelson and Rodney be redesigned for 28 knots?

How late could Nelson and Rodney be redesigned for 28 knots if Italy laid down new Caracciolo-class ships?

The design could theoretically be lengthened and given more machinery, but an early Italian challenge might instead justify extra F3-type ships. A later treaty-compliant Italian programme would come after Nelson and Rodney were already too far advanced.

A two-shaft arrangement does not by itself rule out 28 knots: the F2 and F3 studies provide counterexamples to that claim. Lengthening Nelson and Rodney and adding machinery or shafts is considered theoretically possible, but the resulting changes would create treaty difficulties. Timing is decisive. If Italy used its permitted later building window, Nelson and Rodney would already be too far advanced for the proposed response. An early Italian challenge could instead support a British demand for two additional F3-type ships, retaining Nelson and Rodney and replacing older 13.5-inch ships. Within treaty limits, an Italian design would also face a choice between higher speed with weaker protection and a slower ship protected against its own guns.