Ten minutes later, journalists gathering for Labour's morning press conference were handed a printed statement from the shadow Chancellor, Gordon Brown. "This morning," it said, "Michael Jack, Treasury minister, refused to say how the Conservatives would pay for their commitments."
The speed of the reaction was not exceptional. In this election, more than ever before, swift rebuttal and tight control are the key words of the parties' media strategies.
Special units run by both Labour and the Conservatives are there to ensure that no claim goes uncontradicted, no change of stance undetected, no opportunity missed.
And the strategy does not end there. Early morning briefings are carefully controlled. Earlier this week Mr Brown's press officer, Charlie Whelan, was filmed giving increasingly frantic hand signals to his boss as an event over-ran: two fingers for two more questions, then one finger, then a throat-cutting motion.
Spin doctors sit or stand at the back, pointing out the whereabouts of favoured journalists and preparing to add their own briefings at the end. They help to ensure that the hierarchy of the press is maintained: BBC or ITN with the first question, other broadcasters and broadsheet political editors next. Tabloids and other assorted hacks take pot luck but usually find that Brian Mawhinney is by far the most even-handed in his chairing of the Conservatives' briefings.
Even the least favoured journalists do get to ask questions, though they do not always get answers. Peter Hitchens of the Express, who had clearly turned up at Labour's briefing yesterday to cause trouble, protested that his question about Mr Blair's choice of school for his children had not been met head-on.
Mr Blair responded that he had been kind in even taking the question, and added: "Try to contain yourself, otherwise we might not call you again."
The number of politicians who speak at such meetings is strictly limited.
The anchormen - and they are all men - are usually Tony Blair and Gordon Brown for Labour, with Robin Cook making the odd appearance, John Major and Brian Mawhinney for the Conservatives, with Michael Heseltine bringing up the rear.
Labour seems to have a "statutory woman" policy: there is always one on the platform, but her main contribution is to read a prepared statement. On one occasion Margaret Beckett appeared but did not say a word, and on another Ann Taylor's statement was not read at all, but handed out afterwards. The Conservatives and Liberal Democrats are not so fastidious.
The substance of the briefings is beginning to find a pattern.
The Liberal Democrats, who kick off at 8am each day, try to set the tone with a statement on policy - education, crime and health so far this week.
Labour always attack the Tories but follow the agenda of the day while the Conservatives always attack Labour but the strategy varies.Reuse content