Where's George? Help set the pre-budget credibility test for that tax-cutting spin

Next Left went to the trouble of offering a fact-checking prebuttal of George Osborne's topline 'key budget pledge' claim in a major speech said to be coming today.

Osborne was planning to promise to cut [personal] taxes for everybody on under £35,000, even though everyone concerned would actually be paying more in tax.

It is naturally perturbing to find that this pledge has got stalled on the grid today. Paul Waugh plays Sherlock - and is onto The strange case of the missing Ozzie speech.

But when I ask whether there was ever a Chancellor speech planned for today, I get radio silence. The only line is that the prebrief on tax was not a preview of anything.

This is all a bit of a mystery. Osborne quite often lines up an op-ed if he's planning that same day to give a speech where he can expand on his theme and deliver an even bigger story.

More importantly, if the Chancellor is indeed going to announce a Budget that means everyone under £35K will have a lower personal tax bill, that's a hell of a story.

So good in fact that it could be the top-line the day after the Budget (along with something on cutting fuel duty I guess).

So why has it been floated into the ether only to be followed up with...silence?

It would be a hell of a story IF it turned out to be true.

It would be rather an embarassment if it fell apart within hours - like the "progressive" claims in both June's regressive budget and October's regressive spending review.

But it would be something new to open your budget topline to evidence-based rebuttals from minus three weeks onwards.

Still, we can but admire the Chancellor's commitment to increased pre-budget transparency and scrutiny, no doubt in an attempt to avoid the type of rabbits out of hats last minute trickery that can undermine economic plans.

So here's our pre-budget assignment for leftie bloggers and neutral newsdesks alike.

Please help us to set the George Osborne tax cut credibility test:

* What would George Osborne have to do to make it true that everybody on under £35k had got a tax cut while he was Chancellor?

* And how far short of living up to the spin will he be if he simply puts another tranche into the income tax threshold?

Extra credit for particularly pretty graphs.

We'll try to have a round-up when we preview the budget.