It seems that nobody here is following the latest events unfolding in the US, more specifically those between the partnering companies and the Pentagon/DoD.
General Bogdan and the other parties of the evaluation and acquisition departments are on the war pad against LM and consorts with the property rights as the big objective.
What they will do if they get what they want, be it partially or as a whole, is going to upset the work share among all partners drastically, 15% for the UK might be believable 10 years ago but it seems ever more likely that these "agreed upon " percentages and numbers are no longer guaranteed once full scale production comes into effect.
Basically the lowest bidders will win, thereby sharply reducing profit margins (and therefore also tax returns to the UK government) and making long term contracts (10-20-40 years) ever more unlikely for most of the F35 parts, certainly the more basic, simple pieces.
Like said before , the biggest winners might well be the later entries, non-tier customer-countries who can negotiate offset packages completely separate from the rest of the original partnering nations.
With a program of this size whereby much of the future of both the industry and Air Forces is betted on 1 single candidate many things can and will happen.
First and foremost, the biggest client, the US will simply not allow that the US work-share diminishes too much, much of the support in congress comes from the fact that 48 of the 50 states are actually getting work out of the F35, the support for this project is directly related to the work share these congressmen bring home.
Second, if the US can save billions by choosing alternate sources, something that can be triggered by such an arbitrary ,but almost non steerable, event like a high pound vs dollar price, they will not hesitate to pull work out of the UK, Bae might still get it but Bae can also mean Bae Australia or Bae Canada or Bae whereverelse.
Third,.. for those contracts that can be negotiated there are also the other Tier 2 and 3 nations that can and will bid, I doubt that they will simply roll over easily and leave the ever diminishing piece of the pie to the UK or any of the other competing partner countries/companies.
Believing that the F35 comes free is just wishful thinking, on the contrary, just look what happens when you don't support your own industry, today EADS announces big layoff rounds, jobs that will most likely never come back.
I won't go as far as saying that the F35 is to blame, but it certainly didn't help, the problem in the long run is that you loose this potential and it will be very hard, if not almost impossible to get it back.
Something the UK should know better than anyone else.