Pug
If you look at where the US CVBG are currently deployed away from CONUS, ALL of them are in the 5th or 7th Fleet area. The ones in 2nd/3rd Fleets (CONUS) are either in post deployment stand-down, refit / refuel or pre deployment work up. That means that there is a gap EastLant and the Med (6th Fleet) that would usually have a US carrier deployed and that is precisely where we (and the FR) can add real value.
I'm not for one minute suggesting that we fill a slot in 5th/7th Fleet as a matter of routine, or resurrect the Far East Fleet - far from it. The Pacific-centric nature of future US engagement is old news, they have been working towards this since 2006, it's just that Europe hasn't listened. A UK/FR commitment to provide a "real carrier" in areas where the US recognises a need to have presence, but due to commitments elsewhere cannot actually provide a carrier is what I meant by "effect". Might have to take a turn occasionally in other areas, but that is more likely to be when all is going to ratsh1t, in which case the UK is unlikley to have higher priorities.
As far as UK priorities are concerned, as with all these things, it's a matter of making choices. If SouthLant became an issue, you disengage from your presence mission and head south, with all your stores, airgroup personnel and log support already in place. No different from having a land-based squadron committed to a particular op and then being confronted by another priority - only potentially more supportable.
You'd think that a co-ordinated UK/FR carrier force able to operate in the EastLant, SouthLant, Med would take care of most of the likely UK areas of interest.