The Liberal Party, kind and considerate lot that they are, regularly email around their attack lines. Their response to Kevin Rudd’s slip with tax rates kicked off: “Kevin Rudd has today again demonstrated the risk his inexperience would pose to the Australian economy…” Which is complete tosh – and ignores a more relevant line of attack they’ve been running all week.

On one level, Rudd’s slip yesterday was just an upmarket “What is the price of a loaf of bread issue?”, that famous Ray Martin/Paul Keating moment. But on another it’s a slip that strikes at the Labor leader’s entire political persona.

Kevin Rudd is quite happy to be portrayed as a wonk, as wonks don’t frighten the horses. Wonks might bore you, but they don’t alarm you. Kevin Rudd wants to be seen as risk free. A safe pair of hands. But wonks are also supposed to know details, and Kevin Rudd got a detail wrong. Some politicians can get away with that: populists. Others can’t: wonks.

Kevin Rudd falls into the second category, yet there are occasions when he seems to have difficulty with the details. They aren’t immediately to hand. Or they’re skimmed over. Or ignored. Think of his recent rent assistance photo-op and the fall-out that followed.

When things go wrong, Rudd becomes a big picture man. He sets up committees to look at issues. Which makes those Government lines from earlier in the week claiming Rudd is a phoney ring truer. After yesterday’s slip, corridor talk about a six week campaign hotted up. The longer the Labor leader has to spend on the campaign trail, government figures feel, the more chance he has of running into a c-nt in a cake shop.