Due to our skintness
I think it is cheaper to embed the pilots and selected deck crew on US and French carriers (given that we already run exchanges and already have a 50 year defence pact with France) then have them flow into instructor spots in those two navies so by the time we get to 2018 we've had several people aboard large carriers and Marine core gators. Rather than doing a work up from scratch.
Given that the F35 is a supersonic combat jet and far bigger than the harrier I suspect that a lot of the handling procedures and other elements are going to have to be cribbed off the US and French who have experience with large carriers whereas ours went in 1976 or so. Surely it's better to get the experience from experienced users who have been continously putting the theory into practice so there's a trained experienced cadre that had direct access to US/French experts while they relearnt all the skills that we used to have.
What's the point in continually refining harrier tactics et all when the replacement jet is a multi-role supersonic strike aircraft with an electronics fit more in keeping with the kit thats on US and French combat jets as opposed to the GR harrier?
We have 36 fixed wing pilots in the FAA from memory and I think we currently have 18 on exhange with more to go out. I also remember reading about a couple of meterlogical officers having been seconded to a CVN also