The thing is that capital ships are EXPENSIVE, especially to pay yearly salaries for. Getting both Invincibles AND Vanguard isn't a choice you get to make because of expense. It's one or the other.
Or you improve Britain's economy and do a better job of industrial and economic planning. Now, you have a point about such ships being expensive. But once built and operating, they aren't that expensive. Certainly less than a carrier, which will even in peacetime frequently lose aircraft to accidents and the like.
OK, I now think a BB would've been likely DISABLED instead of sunk - still made useless, though.
Aside from a tail shot causing flooding in the engine rooms or a modern torpedo under the keel, these things are hard to sink OR disable.
I've looked up WW2 aerial torpedos, and see they ranged from 1500-1800 lbs. But, I'm not seeing why Exocets would'nt've done plenty of superstructure and control damage, esecially since they had very high hit rates.
Exocets are designed to be sea-skimmers. The one that hit
Sheffield went through the hull, as did the ones that hit
Atlantic Conveyor. If an Exocet hits the hull of
Vanguard, it would strike the armor belt and that would be it - an Exocet, with its 360-pound warhead, isn't gonna do much more than scratch the paint and maybe cause small fires. Against the Argentinians, she would have been nearly invincible. As CalBear pointed out, most modern anti-ship weapons are designed to deal with stuff much less armored than
Iowa or
Vanguard. There were dozens of cases during WWII of heavy bombs hitting battleships and not wrecking them, including both
Iowa and
New Jersey, which took bomb hits during WWII. The losses at Pearl Harbor were from AP bombs (and a lot of torpedoes - and the loss of Arizona was a
very lucky shot), which the Argentinian Air Force didn't have.
I'm dubious a BB in active inventory would've prevented the Falklands, either. After all, the world knows they're OBSOLETE.
The world knows they cost a lot to maintain, and are less useful than an aircraft carrier. Obsolete, no. Too expensive for most countries for what they will be used for, yes. There isn't many ways to say "fuck you" like a 15" shell from
Vanguard, or a 16" from an
Iowa, and if you were serious about it, modern shell design with base-bleed and GPS guidance, like the US Army's Excalibur shells, could give a battleship greater range and much greater accuracy. Not likely, no. But technology could do wonderful things to a big gun blaster.