From an outsiders perspective going back to the B seems like the least-worst long term solution.
Apart from all the tactical and technical reasons why it is better to go with
the C vs B , when it comes down to finances this latest decision can only
be regarded as an example of being pennywise but poundfoolish.
Yes they (might) safe 1.2 or even 1.9 billion£ by choosing the ramp vs the Cats
but that will just leave them with a substantially more expensive F35 version, both purchase-price wise and when it comes to the rest of the life-cycle costs.
50 planes for one carrier , or let alone 100 if they decide on getting them both operational far exceeds the costs of implementing (a one time cost) the CATOBAR system.
Also it firmly sets the RN with their backs against the wall when it comes to their future options of wanting less expensive planes for other roles.
When things turn better for the economy in a couple of years and (by some unspecified miracle of destiny) the RN gets the money and has a need for its second carrier (due to whatever crisis may come up by then), they'll be at the mercy of LM to provide them with a full compliment of fighters iso being able to do the logical thing and get a couple of F35's for what they are useful for (1st day war etc...) and get some cheaper supplements to do the rest.
T45 Goshawk for Air Support
F18 SH
Rafale's
old Buccaneers for some odd attack roles (<-- okay maybe a bit far fetched)
UCAV's
.....
This whole double U-turn is completely retarded except if you work for RR and have a stake in the F35b engine.
edit for PS;
Like others said before, I also highly doubt the costprice quoted by the shipbuilders for modifying to a CATOBAR system, this has a strong smell of trying to hide other costoverruns and hoping to get away with it, don't be surprised if in a couple of years when they've chosen to go for the ramp and the F35B there will be another surprise budget overrun of at least half the money they're talking about now.