A speculative successor to gas-turbine carrier propulsion

Would the Royal Navy's next carrier generation be nuclear-powered or continue with conventional propulsion?

The present ships use gas turbines; nuclear power is possible, but the answer considers hydrogen a likelier successor to gas.

The answer first corrects the premise that the current carriers are diesel-powered: they use gas turbines. A future class might use nuclear propulsion, though a move from gas to hydrogen is considered more likely. This is explicitly speculative and does not describe an approved design or procurement decision.