The biggest single factor in schedule slip and cost growth has been politics and not just for the carriers but for every single program, defence or otherwise, government has a hand in.
The only reason there are two carriers and that they are the size they are is because that is the bare minimum that could be justified, had it been a frigate, submarine, fighter or armoured vehicle program, numbers would have been slashed in addition to the project being delayed.
The argument that the RN should have acquired a larger number of smaller carriers is great in theory but fails in practice, because, although it is true a given capability can be divvied into smaller packets, this increases overheads costs and it also attracts cost cutting in the form of reducing numbers incrementally. There were meant to be five Escort Cruisers and three strike carriers, this became six through deck cruisers (I believe up to eight were first proposed) and no strike carriers, only three eventually being ordered. The three was cut to two and would have stayed there but for the Falklands War, the capability being retired altogether but for the constant demonstrated need meaning at least two had to be retained.
The government has demonstrated that no more than two carriers will survive the electoral and financial cycles, but no less than two will always be required. All the political penny pinching and changing direction does is drive up costs through stop start stupidity. The need for the capability exists, it is affordable and sustainable, the issue is the political games that drive up the lifecycle costs. Every short term cut increases life cycle cost, every cost cutting change in direction or support, drives up lifecycle costs, every early retirement or layup, results in a capability gap that is more expensive and time consuming to fill.
The worst part of the situation is multiple, large, long term sacrifices have been made to pay for the capability, i.e. combatant numbers, submarine numbers, the LPH, Largs Bay, Sea Harrier and then Harrier, manpower, RFA numbers. All these things were sacrificed, over twenty years, to pay for the required smaller (but more capable fleet), built around two carriers, but those sacrifices have been ignored with politicians, civil servants, media and interest groups now pretending that the RN has somehow foisted this unrealistic, unachievable "white elephant" on the UK without factoring in the cost. Wrong, they have already paid for it through sharply reduced fleet size and painful capability gaps, they have taken hit after hit, economy measure after economy measure and now the powers that be are trying to justify not delivering on their part.
