Sweet timing indeed for Peter Costello and MUP, to announce his memoirs on the day polling shows 38% of Coalition voters – presumably they polled all eight of them – preferred him as Opposition Leader. This prompted Costello to break his near-monastic vow of silence to utter standard words of support for his leader.

Presumably Costello figured the sooner he did the whole memoirs thing the better, because his value declines every day that passes.

However, it doesn’t signal the end of his political career. Liberal insiders are no clearer on Costello’s intentions now than before, which is to say entirely unclear. He’s not saying what he’s doing, except that he’s being Member for Higgins. And memoirs are not necessarily an insurmountable barrier to further political success. Memoirs can be a Latham-like torrent of bile, settling old scores and dumping on the ungrateful party that failed to see the author’s self-evident brilliance.

But they’re also a way of rewriting history and the subject’s place in it. While Labor is busily rewriting the Howard years as ones of social brutality and policy indolence, Costello’s real fight over the narrative of the Coalition’s decade-plus in power is with John Howard. Costello’s memoirs won’t just be a chance to let fly at the latter’s failings. They’ll be an opportunity to re-cast himself in a more favourable light. We might learn about how a Costello Government would’ve signed Kyoto, issued a proper apology to the stolen generation, removed legal discrimination against same-sex couples or left Iraq earlier.

Don’t expect to see much of the Costello who begged off a fight for the leadership after Downer imploded, or who spent 11 years as Treasurer without a serious policy agenda, who let his Prime Minister turn a Coalition Government into the most appallingly profligate pack of porkbarrelers in Australian history, who didn’t have the stomach to seriously pursue his leadership ambitions even after being repeatedly snubbed and insulted by Howard. Even after it was clear Howard was leading the party over the precipice.

Costello has spilled his guts before, of course. Chiefly for Van Onselen and Errington’s book on Howard, and for Four Corners earlier this year. But in neither case did he control the process. This time he’ll have his own father-in-law writing it for him (who said only footballers needed ghostwriters).

If he returns to the leadership, the memoirs will have done a nice job of repositioning him. And, really, unless they contain some hitherto-unrevealed shocks about the Howard Government, they’re unlikely to provide a great deal of additional ammunition for Kevin Rudd, who’ll be sitting opposite Costello at the Despatch Box with a marked-up copy. Labor’s attack lines on Costello are already well-prepared: the gutlessness, the policy laziness, the profligacy of a Treasurer who wasted the minerals boom.

And if he doesn’t return, if he walks out tomorrow into corporate life, he’ll remain the unknown possibility, on whom every Liberal can project their if-only fantasies as they endure the long years of Opposition under Rudd.

It’s typical of Costello, though, that even months after declaring he was pulling the pin, he still hovers at the edges of the political scene, unwilling to plunge in but seemingly unable to walk away. Can this bloke EVER make up his mind? If there’s one great unknown that everyone would love to see in his memoirs, it’s an explanation for his Hamlet-like indecisiveness, the apparent reluctance to commit, to sit back and wait.

But maybe he himself doesn’t understand it.