The US Govt are already saying they have yet to be consulted on the deal - doesn't take a reading age much above that of a 5 year old to work out what they are saying there. Plus the Spanish govt also have a minor stake in this and have yet to agree to it.
Plus the fund managers and banks are also now starting to realise just how many hurdles there are to this and the respective share prices have already dropped. It might be a good idea on paper, but I just can't see it happening.
But then again, over the years, we have sold off so much of our strategic infrastucture - airports, power generation, utility companies etc etc etc to the highest bidder, I very much doubt that Cameron et al will bat an eyelid at the thought of letting the final vestige of the UK defence industry slip into foreign control. If / when this deal does go tits up, it will be because investors realise it's a bad deal not because of strategic concerns.