Perhaps because he is such a has-been, the Ivor Callely expenses row seems less central to our political system than, for example, the fortunes spent on travel and accommodation by certain ministers such as John O'Donoghue in the course of their duty.

It's hard to say what Callely's Fianna Fáil colleagues are more upset about: the fact he claimed mileage allowances from his holiday home in west Cork when his family home was in Dublin, or that he snubbed the Taoiseach Brian Cowen by failing to provide a written explanation for his €81,000 claim. Then we discover that Callely is not alone. Senator Larry Butler – part of Fianna Fáil's team in Dun Laoghaire – has claimed mileage from a second home in Graiguenamanagh, Co Kilkenny, despite the fact that he is registered in Dublin's Foxrock.

And Fine Gael's health spokesman James Reilly has claimed for overnight expenses in Dublin, rather than driving 18 miles home to Rush.

No doubt, more members of the Oireachtas claiming less than legitimate mileage – all within the complex rules, of course – will emerge from the woodwork. They will belong to all parties. Why are we not surprised?

The expenses regime has since been reformed, although the new system is far from ideal. But if politics is to retain credibility, all leaders must insist that there is a thorough audit of claims made over the last Dáil term.