One of the benefits of being a retired politician is that you no longer need to keep half an eye on the electorate when defending yourself. Tony Blair takes full advantage of this liberty when called upon to defend his record, whether over Iraq or at yesterday’s Parliamentary enquiry into the Northern Ireland Office’s “comfort letter” amnesty scheme.

Whilst admitting responsibility for failing to construct a better-run scheme that would have avoided the collapse of the Hyde Park Bomber’s trial (itself a significant admission), Blair was absolutely unapologetic about the issuing of comfort letters to “On the Runs” (OTRs).

These were suspects wanted in connexion with incidences of Republican terrorism who were told, very quietly, that the police weren’t after them any more. New Labour veterans of that era, including Blair himself and former adviser Jonathan Powell, insist that it was not a “secret amnesty” despite being, to all appearances, just that.

To Blair’s mind, the scheme was a necessary accompaniment to the release of Republican prisoners that was taking place at the same time – including the would-be assassin of Margaret Thatcher, Patrick Magee. It was a similar “get out of jail” card for those Republicans who were not yet actually in jail.

The former Prime Minister was absolutely insistent that the entire peace process hinged on the deal, although his interrogators were sceptical. He even went so far as to warn Theresa Villiers, the Northern Ireland Secretary, not to revisit the process lest she put what is now known as “the peace” at risk.

Blair’s performance raises many questions, not least of which was why, given the robust case he was able to make for his conduct, he was so desperate not to have to make it. It is an unusual “administrative scheme” which leaves a former Prime Minister begging the Speaker to spare him explaining it to Parliament.

But it also raises again the problematic question of what price we should be prepared to pay to secure “the peace”.

To state the obvious, Belfast and Northern Ireland are in much happier circumstances today than during the depths of the Troubles, and in many respects than the long period of stifling one-party rule that preceded them. Whilst deep divisions remain polls reveal a growing acceptance both of a shared “Northern Irish” identity and of the territory’s constitutional position.

As I never get tired of pointing out, a majority of Catholics have told the Life and Times Survey they favour the British connexion, even as Protestants cease to be an absolute majority across the six counties. Belfast is a close contender for my favourite British city, and without the omnipresent threat of violence Northern Ireland is now better able to attract both the tourists and inward investments its lamentably state-dependent economy needs.

So it is clear to see why peace is something worth preserving. But we should not allow “the peace process” to become a catch-all excuse by which difficult decisions are either excused or placed beyond criticism.

Making the preservation of peace your highest and overriding aim places one at a profound disadvantage when dealing with men and women of violence, as it allows them to dictate the course of events.

Hard-liners on both sides of the divide used this knowledge to successful edge out their moderate rivals in the 1990s and 2000s. It was once remarked, I forget who by, that neither Major nor Blair would have been so keen on restoring devolution to Stormont if they had known that the Democratic Unionists and Sinn Fein would become Ulster’s largest parties.

Yet how could the moderate parties, like the nationalist SDLP, ever hope to secure as many concessions from Westminster as their less palatable rivals when they had no murderers to rein in, no armament dumps to decommission? An unintended effect of the British Government’s determined pursuit of peace and the rule of law was to sideline the peaceful and the law abiding.

Today, Northern Ireland’s political classes still try to use the apparent fragility of “the peace” to screw more pork out of the British Government. Yet when the Government stands its ground – as Cameron did over the welfare reform crisis – Sinn Fein caved and there was no return to civil war. There is a lesson in that.

It is right to cherish the peace and prosperity of today’s Northern Ireland. But if the Government is not to be held to ransom by hypothetical gunmen – and if it is to hold yesterday’s politicians to account – it must always be clear that its tolerance has clear and identifiable limits, and that it sees more to Northern Ireland than a ticking bomb.