GZip - it's not quite that simple!
The TTSC aircraft will be around 20 years old if they enter service with the RAF - and would then be expected to keep going until they're 45 years old or thereabouts. They haven't been sitting in the desert doing nothing for the past few years - or in bags at Abingdon - but have been in busy revenue service! Also, they are quite different to the US KC-767A being based upon the 767-336ER and not the 767-200. The engines are also unique amongst 767s in being Rolls Royce RB211s....
The fuel capacity is 73.5 tonnes whereas the A330-200 offers 111 tonnes. The A330s are being offered as new-build, although 'pre-owned' ac are understood to be on offer as well. But they won't be nearly 20 years old like your 767s will be!
Regrettably its been a long time since the dear old Vickers Funbus was allowed to fly at such speeds as you quote!
BA's marketing decisions will be unlikely to influence Whitehall, I would hope. In any case, surely Boeing will try to sell you the 7E7 which will be their 757/767 replacement? Whilst you've got 747s and 777s in your large ac fleet, can you really see them letting Airbus win?