Try as they might, apologise as frequently as they can, neither David Cameron nor Gordon Brown can escape blame, even from their own sides, for the great expenses scandal. Reflecting on the past few weeks, Lord Tebbit, the former Conservative party chairman and Thatcherite hard man, believes that the Tories were wrong to oppose Brown’s widely ridiculed performance on YouTube on 23 April, during which he called for the abolition of second home allowances. The employment minister under Margaret Thatcher unfashionably backs Brown’s abortive attempts at reform. Had they been ­allowed to succeed, MPs would be less on the back foot than they are now, as they squirm in shame and embarrassment. “I agree with Brown that it is for MPs, not others, to make the rules. If they can’t be trusted to do that, then what can they be trusted on?” Speaking after attention switched to outlandish claims by Tory MPs – for work on swimming pools, a chandelier and hundreds of sacks of horse manure – Tebbit told the New Statesman: “What you have is people of all styles and incomes on welfare.”

Tebbit’s style could not be more different from that of Cameron’s high-living front bench. His long-time secretary Beryl Goldsmith recalls alerting her boss 25 years ago that he had not claimed his parliamentary allowance. “You don’t have to claim it,” was his reply.

Now, his current successor as Conservative chair, the similarly plain-speaking Eric Pickles, is said to share grave concerns about the damage that has been done to the party’s image by recent revelations. He is believed to have backed calls privately for Cameron to remove the whip from some of the worst offenders. Revealingly, Cameron resisted such a move. At one point during his press conference on Tuesday 12 May, the Tory leader even fell back on blaming the Commons fees office for insufficient rigour in checking MPs’ expenses.

Charles Clarke, big beast of the Labour back benches, is naturally more concerned with the “destructive and damaging effect” the revelations have had on Labour and the government. He believes that Brown has been behind, not ahead, of the curve on the expenses issue, at first blaming the “system” before joining Cameron to offer a belated apology.

While the Commons is united in shame in the wake of the cross-party expenses scandal, a new fault line has emerged among MPs over how best to limit the damage. Some, including Clarke, believe that parliament should take the lead by publishing full receipts now, in order to remove the “ransom” held over it by the Telegraph newspapers, whose investigation is said to have amounted to a six-figure payment to a source – chequebook journalism by any other name.

Clarke says full disclosure of receipts, rather than pursuing the leaker (or seller) of the details through the police, is the right priority. The Labour backbencher Kate Hoey agrees. When she made the case for transparency over a leak

investigation in the House during the week, she was angrily rebuked by the Speaker, Michael Martin, for what he called her “pearls of wisdom”.

The Speaker, who reportedly told one MP that he “did not come into politics not to take what is owed to me”, is personally implicated in expense scandals, with his own claims under scrutiny. Worse still, Martin is seen as having presided as the de facto shop steward of a closed shop. As one Commons official said privately about the latest revelations: “We [officials and journalists] all knew it was happening, but they [the public] didn’t – until now.”

There is a growing consensus that Martin must step down. Ministers have advised Brown that progress can be made only after the Speaker’s removal. Charles Clarke told me that Martin’s behaviour was “utterly deplorable”.

Today, it is harder than ever for less cynical observers to argue with justification that Britain’s politicians are among the least corrupt in the world. MPs of all sides have been proved to have gone well out of their way to play the system for all it was worth. We were only following the rules, they said initially. Adolf Eichmann said something similar when he was on trial for genocide in Jerusalem. Rules may be rules (or the law, in the case of Eichmann), but why did MPs not seek to challenge them, seek to demonstrate that the rules on expenses were wrong and in need of reform?

It is worth mentioning, however, the few MPs who, claiming only minimal allowances, emerge with honour from this scandal. They include the Conservative MP Philip Hollobone, the Environment Secretary, Hilary Benn, the Health Secretary, Alan Johnson, and the Climate Change Secretary, Ed Miliband.

Miliband’s decency is not confined to expenses: he is one of very few MPs, along with his brother, the Foreign Secretary, David Miliband, to have no outside financial interests. To the younger Miliband’s civil servants, this is no surprise. They were endeared to their minister when he was handed the new department last year. With no proper office, he “mucked in”, according to mandarins, without a trace of presumption or pretence. As a Brown supporter who is respected by Blairites, Ed Miliband holds a unique position within the Labour hierarchy. Last summer, when his brother was perceived to have challenged Brown for the leadership, was a particularly uneasy period for him. Yet he remained loyal to the leader, being the first to defend Brown after the disastrous Glasgow East by-election defeat last July, as he did again after the exposure of Damian McBride. He had previously warned Brown about McBride’s underhand work.

Ever optimistic as well as loyal, Ed Mili­band still believes Brown can win the next election, but he is in a rapidly shrinking minority. During the week, I bumped into a senior minister who not long ago had said that Labour could still win the next general election by concentrating on economic issues. Now, he said: “It’s all over. It’s a slow-motion car crash and there is nothing we can do about it.”

Yet if – as Ed Miliband believes – an election is still a year away, and if Labour can somehow reform the expenses system and then start to concentrate on the economy, the election can still be won. After all, the Tories, with their claims for swimming pools and moats and piles of manure, are even more contaminated than Labour MPs by the systematic abuse of expenses.

One thing is certain after this scandal, however: that an alienated and sickened electorate will offer one of the lowest turnouts in modern political history.