But I don't think the Brazilians could buy a design/build locally a meaningful CV for £1bn and as I have said before what better airdefence could they get than 2 T45 (or even 2 RN T45 & 2 local built)..
Here we go again . . .
You keep ignoring the main factors, i.e. politics & industry. It's like the new fighters: the Brazilians don't want just aircraft carriers, they want an aircraft carrier building industry. They're not thinking about buying a ship, but a long-term capability. They know that buying an already-built ship, even at a giveaway price, won't get them that. As well as industry & the navy wanting home-built, there are also political obstacles to ships as big as CVF. I keep saying that, & you keep ignoring it.
As for what they could get for £1bn, well . . . . considering what Cavour cost, & that costs are lower in Brazil, I reckon they could get most of a 40000 ton or so carrier. For £2.5-£3 bn or so they could probably get two, which is what they want.
Type 45 is
expensive. If we sell two for knock-down prices, what do we do for naval air defence? How much would it cost to replicate that capability? You're proposing we gut the RN, & sell off ships for a fraction of what they cost to build, or would cost to replace. Also, the Brazilians could almost certainly build Italian FREMM copies for much less than Type 45s, & while not as capable, they'd be perfectly capable of handling anything they're likely to come up against. They'd also give the possibility of commonality across the fleet, if they get a mix of AAW & other (e.g. ASW) models, which we can't offer with the T45.
You're still letting your vision of the future needs of the RN override what you know about the need to sell what the customer wants, & trying to foist on Brazil what you think we can sell, not what they want or need.
What I am suggesting is simply do what the French/Swedes/Israelis/Russians and everyone else is doing, but the RN is too arrogant to lower itself to helping British industry. In the past the RN has given up its ships for replacement later.
The RN has already given up most of its fleet, & is about to give up even more. Two carriers, an LSD, support ships, & four frigates are in the process of going,
some of them to be replaced later. It's doing what you ask (apart from building ships to exportable designs, where I agree with you), but you want it to go even further, to the point where we'd hardly have a navy.