Would nuclear power have prolonged British capital ships?

If the Royal Navy had nuclear ship propulsion from 1945, would it have retained its large ships longer?

Probably: they would still age, but low fuel demand and the need for fast nuclear-carrier escorts would make retention more attractive.

Nuclear machinery would not eliminate structural wear in British capital ships. It would remove much of their conventional fuel burden and increase the incentive to retain such expensive hulls. Nuclear-powered carriers would also need escorts able to keep pace without frequent refueling. The large ships might survive in that role unless Britain built a new generation of nuclear cruisers instead.