Displaying the cockiness which perhaps goes with their background, and which could become more apparent as the campaign goes on, the Tories are claiming a near knock out blow.

George Osborne’s people are busy making him the ‘zero to hero’ star of a clutch of articles, of which expect many more in the Sunday papers, suggesting his planned non-rise of National Insurance Contributions is a game-changing election winner.

There will be plenty of ups and downs in the coming weeks and it is good to see that Osborne himself understands that.

Pointing to the importance of the leaders’ TV debates, he says election campaigns only work if they highlight work that has been underway for years. ‘You cannot fatten a pig on market day. The change has to be real and the policy positions have to be strong.’

Exactly right. I know his words were meant as a dig at GB. But they encapsulate why ‘sums don’t add up’ attacks on the Tories have a lot of a traction left in them, more so since the NICs plan was announced.

* Buy The Blair Years online and raise cash to fight the Tories http://www.alastaircampbell.org/bookshop.php.