I think the pre 57 DWP proposals depend on the RN having a 6-carrier fleet. Once the RN goes from 6 to 4 carriers the number of fighters drops to a number so low that the production run cannot amortise the development costs over a large enough number of aircraft. Added to this is that by the late 50s there is no getting around the long list of non-negotiable capabilities that the aircraft cannot help but being expensive; Mach 2, good around the carrier, all-weather guided-missile weapons system etc.
I don't deny there are a lot of interesting proposals for the requirement, but they will all run up against an expensive development cost and low production numbers with a high(ish) unit cost.
This is why the Minister of Defence, Peter Thorneycroft, mandated in 1961 that all future fast jets should be joint RAF/RN developments.
That was fine and dandy on paper but when NMBR.3 looked like being the next big thing, everything was staked on it and the RAF was on board. Nobody asked the RN if they wanted VTOL. They didn't but had no choice but to buy whatever the RAF wanted - P.1154. NMBR.3 ended up a busted flush anyway, but the RAF was adamant it wanted V/STOL.
When the politicians finally wised up that mashing two different roles into one aircraft wouldn't work, the RN got Phantoms but as a consequence, when the RAF lost P.1154 in 1965, they were automatically obliged to buy Phantoms - which were not suited to ground attack and which led to Jaguar being purchased just the year after.
OR.346 was fantastic on paper, but once OR.356 came along shortly after to replace Sea Vixen, the strike aspects were emphasised as a Buccaneer replacement the RAF of course already had TSR.2 in development so it automatically pushed OR.346 back to the late 1970s as a tentative TSR.2 replacement, making it no good for the RN and having to devise new Bucc upgrades.
Now of course, when TSR.2 died the RAF was not forced to buy Buccaneers - they got F-111K over Bucc 3 (until of course F-111K was cancelled and then there was no alternative but to accept stock RN Buccs).
AFVG was meant to be dual Service but of course that died quickly and of course with the carriers earmarked for the scrappies in 1975 it made little sense then to develop a naval AFVG.
So the whole policy was a mish-mash of confusion with no real operational analysis of what either Service wanted. The RAF backed the wrong horse with V/STOL. Had they preserved with OR.346 for a VG-winged Type 583 it would have saved a lot of hassle. Yes it would have been expensive to develop but it could have replaced Sea Vixen, Buccaneer, Hunter, Javelin. It might even have killed TSR.2 earlier in the development path. The money saved would have been pretty useful all round. Production would be at least 300 aircraft, probably a little higher.
F-111K may still have been sought as a bigger strike aircraft, it might have emerged as a rival had the 583 series R&D costs been too high.
Probably means no Harrier - but hey I can live with that quite honestly.
Also means no AFVG (Dassault gets to play with its Mirage G without interference) and also means no MRCA, at least as we know it, although its highly likely that by the mid-70s the RAF and RN would have been looking at a successor for the early 80s and this probably would have been a European collaborative effort. Probably something like EFA but a little earlier and with a two-seat option.