Re: Let me get this right
Ahhh but the UK isn't just buying it, they're a (the only) Level 1 partner which means they were allowed to define key requirements*, and get to build large chunks of it**. Presumably that also gets you a vested interest in proving it meets the operational reliability metrics.
*Something the MoD were quite reticent to do in case they over-complicated the programme, I think the bird strike resistance of the windscreen was one thing they insisted on hence the internal support that marks the end of the double thickness section.
**The rear fuselage of all of them and the lift fans of the Bs for starters.