Phil,
Not sure I agree. The theory for the bigger carriers was sound. Eventually you have to buy new kit - that's a given. Small carriers and VSTOL aeroplanes will always suffer from performance limitations at some point, be it hot weather bring back, fuel load or getting a specific weapon off the deck. Invincible class ships really started getting complicated with 12 Harrier on them, even with no helos.
Big carriers allow you to operate more capable aeroplanes in greater numbers. I personally believe that you get to a low threshold below which it really isn't worth bothering. In the modern day you need something capable of launching a radar guided weapon air-to-air, using GPS guided weaponry and having SEAD or EA capability.
So big carriers make sense.
Now, if you were to buy two carriers of the same specification then you have redundancy. Simples.
The problem comes when that isn't possible due to budgetry constraints. And carriers are expensive enough for them to be criticised on cost grounds by those who favour land based air. And the more expensive you make the jets the more empty deck you get!
I personally thought that run on of Harrier at the expense of Tornado would give our small island nation a flexible, embarkable capability whilst preserving most of the attack and recce capability the Tornado offered. But the Harrier had dropped from a 18 FE@R fleet to 10 and the Tornado was still up at 40. So it was going to be bloody one way or the other. It went 'the other' and isn't coming back.
I'm not privy to what actually goes on in the towers of power. But what saddens me is that someone, or some people, or a systematic failing caused this. The Dannatts, Bands and Torpys of this world must have known that we were building up the famed £38 billion black hole - it didn't happen by magic. Like I said, I don't know where the blame lies. We just seem to be incapable of buying the right thing for the right price. More importantly we seem to be incapable of accurately forecasting how much projects will cost - so spend a lot of money finding out we can't afford them.
My personal opinion is that QECV and F35C are the right thing to be buying - it's not cheap but it'll last a while.