The problem here is that the UK as a sovereignty is a global player politically for obvious reasons.
Unlike the US we don't have the economy to back that political power up. Yes the PM and senior cabinet ministers need to make many many trips abroad every year to keep Britain in the loop as a key political force but justifying purchasing and maintaining aircraft for the job may not be economically viable - I'm just guessing!
However, I do like the commonality idea with the A330 etc...
