Scenario:
Earlier than OTL reduction of KM surface forces means that the RN focuses on completion of lighter assets, such as Tiger/Lion/Blake, during WW2. Howe and Anson are delayed until after the war's end; Vanguard is never laid down.
Anson and Howe are, belatedly, completed post-war, more or less to their original design. Radar and light AA fittings likely reflect Pacific War experience. They do the stuff Vanguard did historically, into the late fifties or so. There are proposals for radical re-builds with Polaris, Sea Slug, and all that jazz, but nothing ever comes of it.
With mid-sixties manpower problems, the general obsolescence of battleships, and so on, Anson is laid up and cannibalized for parts to keep Howe going.
Howe gets the Tiger/Blake treatment in the late sixties:
-The aft turret is removed and replaced by a big-arsed hanger/deck for ~4 to 6 helicopters.
-The 5.25" secondaries are replaced by more ubiquitous twin Mk 6 4.5" (four lower mounts) and Sea Cat installations (four upper mounts).
-Exocet is considered but never installed.
-New radars and command/control facilities. No sonar because battleships don't do ASW.
She's popular as a task force flagship, but is still a manpower hog, as crew requirements probably stay around the same - reduction of the gun crews is offset by air group and additional command/control people. Odds are she's laid up in the late seventies. Is she re-activated for the Falklands War (assuming there is one)? I dunno.