As the details of today's Pre-Budget report emerge, amid the leaks and pre-briefings, one thing is already clear: Alistair Darling will be more concerned with scoring political points than telling us the truth about the dire state of public finances. With less than 6 months to go before a general election, this is not surprising. But as John Kay points out in a thoughtful FT column today, this Government has a long record of turning Treasury forecasts into political constructs. Instead of "objective, technical affairs" which used to provide important, if complex, information, background papers to Budget statements are now "written in the style of the corporate PR executive." I have blogged here before about the importance of truth-telling to restore trust in politics and, in my CPS report The Reality Gap, identified the technique which Kay describes - Labour's relentless manipulation of data to present the best case scenario. A too-credulous, or plain lazy, media (most notably the BBC) too often presents government material as fact. The result? Opposition parties need to work harder than ever to extract the truth, and should at all costs avoid conducting the argument on the Government's terms. This afternoon, the Conservatives need to be ready to pull apart the Chancellor's claims and make the case for an entirely different approach to handling - and communicating - the state of our public finances. And if anyone thinks that taxing bankers' bonuses will get the British economy growing again, let's hear some economic forecasts to support that contention.