I keep hearing from one or two reliable sources that the F-35B decision is not done and dusted and the possibility of moving the the CV version is still on the table. Going CV would significantly raise the commonality between the UK and French ships and it should also be borne in mind that installing cats and traps is not going to get any cheaper. Yet another risk is that when EMCATS come on stream in the USN, the manufacture of steam cats will cease. If the DoD decides that it does not want to release this technology to its allies how do you launch your aircraft? The UK hasn't made a steam cat for 50 years. CV also brings the possibility of cooperating with the French on a joint Hawkeye purchase. Its no secret that the RN would like to have a proper AEW platform which can accompany a strike package - although UAVs may offer a solution here.