Well-informed readers will remember that inter-war British governments did this with defence plans - the decision was taken that there would be no war for 10 years and this assumption was used as a basis for policy. But the 10 years was considered on a rolling basis, so every passing year extended it further until it was abandoned in 1933, with the result that the British armed forces were just about ready...had the war waited until 1943.
Now you might recall that Gordon Brown also had a set of fiscal rules, and those laid down that the current (i.e. ex-capital investment) budget ought to be in balance averaged over the economic cycle. Put it like that, and you might think that there isn't really that much difference. And we used to hear a great deal from Tories - and even from well-known newspapers dedicated to Liberal principles - about how the judgment of when the current economic cycle began gave the chancellor too much latitude to fudge the numbers. We heard a great deal about this from George Osborne personally.
But now he's apparently thinking of tactfully leaving a bunch of stuff (current, structural) out of the figures to make them add up. And he's quietly letting the day when they have to add up slide right. Fudging the issue, if you like. Just like Crazy Gordon McKiltie Borrowpants. (Did we mention he's Scottish?)
So why is this a secret? Why did the Guardian publish all the information you need to know this, but not say it? Why do I have to read the papers as if I were composing an exegesis of the Talmud or decrypting the VENONA cables? Is it possibly something to do with this quote from Nicholas "You Fucking" Watt's profile:
Even his critics acknowledge that Osborne is tough, which will serve him well, as one said. "George has an incredible strength. Perhaps this is down to the way he made it into the Bullingdon and survived. They were a bit sniffy about George. The Bullingdon is basically for Etonians. But they let him in even though he went to St Paul's, though they did insist on him reverting to his original name of Gideon.
Now that's what I call the sort of experience that builds real character. This is the Guardian! The Guardian!