The fact that the document was inadvertently placed on the Tory Party website and gleefully paraded around the media by Ed Balls helped to make it a disaster. For the first time since being elected leader, Cameron was on the back foot.
The way the Tories presented the tax proposal was poor. It enabled the Government to say that a £21bn tax cut would mean a £21bn cut in school and hospital funding. Moreover, it gave Gordon Brown ammunition, something he hitherto lacked.
He couldn't believe his luck. When Brown sets up his own commissions, he does so only on the basis that he knows exactly what they will say. Those written prior to the landmark 1997 election were almost completely written by the shadow chancellor himself. More importantly, they promised nothing. The only pledge Brown ever made on the economy before gaining power was not to raise the basic rate of income tax.
Cameron tried to use his report to emphasise that there would be no tax cuts and to look tough in taking on those Tories who do want them. The spin was that this is Cameron's ‘Clause 4 moment'. But if that's the case, he faces six Clause 4 moments, because that's how many commissions he has to report.
The strategy may have enabled any Tory being grilled by John Humphrys about lack of policies to say, ‘you will have to wait until after the commissions have been published'. But you just had to see Jeremy Paxman tearing the Tory spokesman apart after the economic report last week to see the folly.
There is also the problem of mixed messages. As any election strategist will tell you, selling one simple message is crucial, yet on the economy the Tories now have two. The party wants £21bn in tax cuts, but the leader personally doesn't.
Back at Labour Party HQ, they can't wait for the next commission to report. What will the Tories do when Zac Goldsmith proposes to put swingeing green tax on aircraft fuel? ‘Tories to stop cheap family foreign holidays' is hardly a vote winner.
What's the point of the commissions if they include vote-losing policies, so that when they report you have to ignore them?
If I were advising Cameron, I'd be looking to bury all commission reports. How about releasing the lot on Christmas Day?