British sources confirm that meaning of "fixed" -- as in "manipulated" or "cooked" -- is the same in Britain and America

In a British Broadcasting Corp. (BBC) documentary from March, which quoted the Downing Street Memo more than a month before the Sunday Times published it, BBC reporter John Ware explained: "By 'fixed' the MI6 chief meant that the Americans were trawling for evidence to reinforce their claim that Saddam was a threat." The headline of a Sunday Times preview of the documentary -- "MI6 chief told PM: Americans 'fixed' case for war" -- also makes it clear how the British understand "fixed."
Similarly, Sunday Times reporter Michael Smith, who first disclosed the memo on May 1, ridiculed the notion that "fixed" has a different meaning in Britain in a Washington Post online chat:

SMITH: There are number of people asking about fixed and its meaning. This is a real joke. I do not know anyone in the UK who took it to mean anything other than fixed as in fixed a race, fixed an election, fixed the intelligence. If you fix something, you make it the way you want it. The intelligence was fixed and as for the reports that said this was one British official. Pleeeaaassee! This was the head of MI6. How much authority do you want the man to have? He has just been to Washington, he has just talked to George Tenet. He said the intelligence and facts were being fixed around the policy. That translates in clearer terms as the intelligence was being cooked to match what the administration wanted it to say to justify invading Iraq. Fixed means the same here as it does there.