Two carriers is the absolute minimum but still constrains effective use in "wars of choice". To use military force to effectively support diplomacy requires the will to take risks. The only answer is a larger force of carriers which can sustain extended deployments and provide a buffer against attrition. Lets hope that after the two CV's are delivered, the UK Govt replaces Ocean and Ark Royal with two F35B capable "LHD's" similar to the Australian/Spanish designs.
I did article on Arrse about future requirements, and I said we should have the 2 CVF's, and as you say replace Ark Royal and Lusty with two upto date CVS's or as you say LHD's that can handle Harrier/F35's this way we would have potientially 4 carriers not two,
Duncan