Steve Richards: Whatever his financial arrangements, Ahern's real legacy is the peace process

Another leader resigns with a whiff of scandal in the air. This time, the resignation comes from Ireland, with Bertie Ahern stepping aside as a tribunal investigates his financial affairs.

From a lofty British perspective, it is tempting to note that, as far as Irish politics is concerned, there is nothing new in this. Nearly always Irish leaders take a bow amid allegations of corruption. We should resist the temptation to patronise. Tony Blair left Downing Street still being pursued by the apparently heroic Yates of the Yard.

For months as Prime Minister, he faced relentless questions about the so-called "cash for honours" scandal. The build-up to his resignation, almost as long as most leaders' full term in office, was punctuated by news that he had been questioned by police and that his close aides had been arrested.

Before Mr Blair, John Major departed overwhelmed by claims that he ran a sleazy administration. Now Gordon Brown governs with at least two police investigations preparing to report on the activities of former cabinet ministers and Labour party officials. It is lucky that the police in Britain are so generously staffed or else they would have little time to do anything else.

The parallel with Mr Blair is most striking. He and Mr Ahern danced together for years in an attempt to keep the Northern Ireland peace process in place. Together, their careers offer two alternative views of politics as a vocation. Both can be cited in different ways by those that despise politics. Yet the anti-politics brigade has a problem in its sweeping condemnation. The peace process in which both leaders played pivotal roles gets in the way of their loathing.

I have no idea whether Mr Ahern will be found guilty of any wrongdoing. I note that the Taoiseach acknowledges in his resignation statement that some people "will feel that some aspects of my financial arrangements are unusual" – a lawyerly, defensive interpretation of how he will be perceived.

Some of his arrangements, such as having no bank account at one point, certainly come into the "unusual" category. Others in Mr Ahern's Fianna Fáil party who have followed closely the tribunal investigations would probably deploy more precise terms than "unusual". The revelations in the tribunal so far would almost certainly have been enough to have brought down a British prime minister long ago – a safe bet given that Messrs Major, Blair and Brown are all associated with corruption without being corrupt.

The parallels are not precise. Mr Blair resigned for reasons beyond the so-called "cash for honours" investigation, not least because Mr Brown had forced him into the artful position of being compelled to resign at a time of his own choosing. Still, "cash for honours" haunted Mr Blair during his final months in office, draining Downing Street of energy at a time when stakes were high on several fronts.

I was always certain – and wrote it here several times – that Yates of the Yard would not have the ammunition to bring charges against Mr Blair and his entourage. The report from the Crown Prosecution Service last summer explaining why indeed no charges would be brought is one of the classic texts of our times, showing why the puny, self-important John Yates, the Assistant Commissioner of the Metropolitan Police, never had a chance to become the officer that brought down a prime minister and his court. Perhaps the investigations into Mr Ahern will be more damning. We will have to wait and see.

But there is another side to politics that the careers of the two leaders also reinforce more vividly than most. In the case of Mr Ahern, I would go as far as to say that it wipes out anything that the tribunal will discover in its investigation. As far as Mr Blair is concerned, it places him on different terrain than the soon-to-be-forgotten Mr Yates.

The peace process remains one of the great advertisements for politics as a vocation. Reading Jonathan Powell's new book about the process, Great Hatred, Little Room, is the equivalent of entering an alternative view of the past decade as he narrates his side of the long road, describing the wilful determination of leaders to bring about peace, to keep the bicycle moving, as he describes it.

No doubt the account is written from a self-absorbed perspective. By definition, most memoirs are. But for those who regard Mr Blair and his court as deranged war criminals, the Northern Ireland story must be something of a problem. Why does a deranged killer spend so much time seeking to achieve peace? As I argued last week, domestic political pressures and calculations propelled a weakly defensive prime minister to war in Iraq. Freedom from such pressures in relation to Northern Ireland brought the best out of him, giving him the courage to pursue peace.

Arguably, Mr Ahern was better placed to embark on the thorny road to peace, used to the complex politics of coalition-building in Ireland. When Peter Mandelson was Secretary of State for Northern Ireland, he used to describe the sensitive choreography as being "one step back to progress, two steps forward". This is similar to what is required to sustain governments under proportional representation in Ireland. Mr Ahern moved one step back and two forward in domestic politics – until he left the dance floor yesterday – and in negotiations towards peace.

Within the slippery, evasive manoeuvres, there were times of more epic heroism, such as when Mr Ahern returned quickly from his mother's funeral to keep the Good Friday Agreement on track, and in the restraint he displayed in draining clashes with David Trimble. In his book, Mr Powell reveals that Mr Ahern left one meeting threatening to hit Mr Trimble, who was also doing his bit for the political process – one step back and two forward.

There are many reasons why the peace process moved towards its fairly secure conclusion. I agree with Mr Powell, who argues in his book that the Government's support for devolution in other parts of the United Kingdom gave legitimacy to a Northern Ireland Assembly. The elected institution in Belfast was part of a pattern and not a bizarre aberration. The soaring economy was a helpful backdrop, too. But politics played a big part in achieving peace, reminding us that the alternative to this much-derided vocation is violence. There are no other ways of resolving conflict and of reaching decisions.

When I bumped into him yesterday, the relatively new Northern Ireland Secretary, Sean Woodward, was able to joke that with Ahern, Blair and Paisley gone or going, he is left with Gerry Adams and Martin McGuiness from the original negotiations – the duo that is still standing after all these years. Mr Woodward knows from direct experience that there are still fragilities in the peace process, but the fact that he could joke about the departure of a pivotal ally shows the degree to which Ahern and Blair made politics work – as they retire in a whirl of sleaze.