Perhaps this briefing needs updating then;
http://www.parliament.uk/Templates/B...?bp-id=SN06278
3 Number of aircraft and basing
The decision on the overall number of aircraft will not be made until the next Strategic Defence and Security Review (SDSR) in 2015.15 The original planning assumption for up to 140 aircraft is not expected to be realised. Defence Secretary Philip Hammond confirmed in July 2012 the UK will order 48 aircraft (including the four test aircraft) with further numbers to be confirmed in the 2015 SDSR.16
The decision taken in May 2012 to use the STOVL variant rather than the Carrier variant will not affect the number of aircraft to be deployed on the Carrier. Twelve aircraft will be routinely on board the carriers with a potential surge to 36 aircraft if required.17
The F-35 force will be operated by both Royal Navy and RAF pilots.