"investing billions of pounds" sounds like a good answer, but ONLY if the billions are in the right area. Billions on 2 carriers without the necessary escorts/aircraft, or a paucity of destroyers/frigates for other tasks, is not necessarily 'billions' in the right place.
As with F35, "hugely capable" T45 only works if you have enough of the asset to be in 2 or 3 places at once.