Ok many alternate back stories such as RN BBGs, RN FAA retains CTOL carriers, RN modernises CLs in to CG, builds new CGs etc. replacement for any or all of these is a RN take on the USN Strike Cruiser concept based on the Invincible Class STOVL Carrier hull.
Real story, I have a Dragon 1/700 Illustrious that is donating bits and bobs to other projects and I am thinking of turning it into a Strike Cruiser with multi-tiered gun and missile armament, retaining most of the through deck but not the ski-jump. Looking at a variety of configurations, maybe a 5" gun in place of Sea Dart, or I think I have a Mk 26 twin 6" from a matchbox Tiger somewhere, Oto Melara Super Rapido 76mm in place of Goal Keeper or possibly arranged differently again. Tomahawk armoured box launchers, Harpoon, Phalanx. If a replacement for the BBGs then maybe the some deck mounted launchers from 1/700 MLRS (if I can find the Skywave / Pit Road kits)
May do an RAN version using US weapons and radars, i.e. Mk 26 GMLS fore and aft the bridge etc.
All up in the air at the moment and don't know how much surgery I will be doing, had thought of sponsons port, starboard, fore and aft with guns and missiles and a wider sponsoned flight deck to offset a bulkier island structure and still provide a decent helo capacity ASW, AEW. Assault and Attack helo types.
Still toying with the exact role of the ships, Command, ASW, Commando (LPH), ASvW, Land Attack etc. escort group leader.