Suddenly Peter Costello is talking, after months of near-total silence. In a good cause, naturally – his own. Or his and his father-in-law’s.

Until they see the book, and – after first checking the index to make sure they’re there – determine how much damage it will inflict on the party, Costello’s colleagues will fret about it. The last thing the Liberals need at the moment is a return of the Costello-Howard rivalry, haunting them even from beyond the political grave of at least one of them.

A key problem for the Liberals since the election has been that they have been the story: they’ve been internally focussed on Malcolm’n’Brendan, ex-Ministers, mooted mergers, you name it. Costello has “first mover advantage”, as one Liberal put it, over Howard, who is also writing up his own rather lengthier public life, and a memoir that exploits that to seriously get stuck into the former Prime Minister isn’t going to do anything to make the Liberals look any less self-obsessed.

Fortunately – or unfortunately, depending on your taste for vituperation – it seems from Costello’s comments that it will be a more elevated effort, complete with “where do we go from here” analysis. Costello has substantial experience in public life and must surely have some genuinely interesting things to say about public policy and economic issues.

It might also give us some insight into the man who, despite his years in the public eye, remains something of an unknown. And not just to the public. A long-standing Liberal colleague said that Costello always played his cards close to his chest; that he made his views crystal clear on economic issues but otherwise kept his views to himself, and accordingly remained enigmatic.

And perhaps that’s the greatest danger for Costello. It’s his silence and restraint that has made him interesting. Given we rarely got a glimpse of what he was like outside the role of Treasurer, we could project anything we liked onto him, particularly progressive Liberals keen to see a swing back from the conservative drift of the party under Howard.

But once Costello speaks, at length, that spell is broken forever. An anodyne memoir that offers only trite observations about the Howard years and Australia’s future will reduce Costello to just another politician, and there’s nothing especially interesting about them, as a rule.

If the book is to reposition Costello for either a return to the leadership, or private life, it will have to offer originality and substance, and it’s not entirely clear from his political career that he has either in abundance.

Meantime, The Australian has been extracting maximum utility from yesterday’s Newspoll in which Coalition voters preferred a Costello-Turnbull team leading the Opposition. You may as well ask punters whether Lillee or Lindwall should take the new ball for the Australian cricket team of the century, or whether Batman could beat Superman. It ain’t gonna happen.

Turnbull’s too ambitious, and Costello knows ambition too well. Still, despite every Liberal who is asked being in furious agreement that Brendan Nelson is sticking around for a few more months of punishment, there’s no end to the leadership talk. Hurry on Budget night.