Both the articles linked use similar figures, but they are, in my view, examples of selective leaking of figures plus uninformed 'spin'.
Leaking a DSTL 'secret' document is a serious matter in itself. However, the figures that are being revealed are not all that surprising. If anyone takes a look at the KPPs for the F-35 variants (open source and dating back to 07) the difference in range of the B and the C have been there for all to see. I have also seen open source briefs from LM detailing fuel capacities of the B and the C. I know that, because I delivered one of them to the RAeS in 2006. From these, it's not hard for a competent performance engineer to derive quite accurate estimates for 'time on station'.
Some errors mixed in with these old facts. The CVF deck surface does not need to be modified to 'protect it' from vertical anding jet blast. Catapults and arresting gear were included in the original CVF design. F-35C increased fuel capacity comes from larger wing tanks as much as the extra fuselage tank. And some partiality as well. The F-35B landing is not 'fuel-guzzling' - do the detailed calculations on fuel burn for a normal STOVL recovery and a normal CV trap recovery, and you find not much difference.
I really do agree with Bastardeaux that this recent 'B vs C' saga has been badly handled by the Government and the MoD. Objective analysis appears to have gone out of the window, and in my view it was a victim of inter-service politics, lack of technical grasp at at higher levels, and plain poor execution of the SDSR. Not good, and seriously damages the Uk's reputation for competence in defence acquisition. Bernard Gray will be looking for a new job soon, in my view.
Best regards as ever
Engines