Nick Clegg: We need to know why we went to war

Earlier this week I met three parents who lost their sons in Iraq. They have campaigned tirelessly for a full, public inquiry into the Iraq war. They are profoundly patriotic men and women, who were proud of what their children were doing in Britain's armed forces. They were prepared, as much as any parent can be, for the fact that they could lose their child.

If they had lost that child in an honourable war, defending the nation, they would have mourned, of course, but with a sense of pride.

They told me that what they find truly devastating, unbearable even, is that their sons' ultimate sacrifice was made in response to false claims from the Government. The government took young men and women who were prepared to put their lives at risk for the sake of Britain's safety – and sent them to meet their fate in an illegal war instead.

One father told me how excited his son was by the extensive training he received to protect himself from Saddam's biological weapons. Now the father knows what his son could not: there were none of those weapons. It was all a sham.

These families simply can't understand why no one has been held to account. How, they ask, is it possible that the most disastrous foreign policy decision in generations, taken on a false premise, can be left unexamined? Will no one take responsibility for what happened? We had the whitewash Hutton inquiry, then the Butler inquiry, but the real truth about the political decision-making that led us into this war has never yet been exposed.

Labour and the Conservatives came together to drag our country into an illegal war: we need to know how that happened so that we make sure it never happens again. The government has finally accepted that it can no longer duck an inquiry. The question now is when and how this inquiry will be carried out.

I believe the inquiry must begin immediately. It must examine every detail the government would rather ignore. And it must be held as much in public as is compatible with national security. So much, and no less, is what Britain needs if we are to move on from this military disaster and regain our sense of ourselves as a positive influence in the world. We owe it to the families whose sons and daughters were lost so needlessly.

Neither the Government nor the Conservatives want the inquiry to be full and open. Both parties would rather not revisit this ground, because they know they can only look back with shame. Jack Straw has already taken the unprecedented step of blocking a valid Freedom of Information request so as to suppress the papers from the cabinet meeting where the Iraq invasion was discussed. And the Conservatives know they cheered the war on from the sidelines, however much they may pretend otherwise today.

But this goes beyond the record of the political parties. It is about finding the truth, because that is the only way we can learn for the future. Britain can and should be a force for good in the world, promoting democracy, human rights and the rule of law. But how can we regain the self-confidence to do what's right if Governments can force the country to do what's wrong?

If Britain is to take its rightful place on the international stage, we need to look back at Iraq, even at the most painful details, to learn the lessons of the past.

This is also about how we are governed, not just the Iraq invasion. We have one of the most secretive and unaccountable forms of executive government anywhere in the western world. Decisions taken on a sofa in No 10 are rubber-stamped by a supine Parliament. A Government elected on little more than 22 per cent of the eligible vote can arrogate to itself a decision to go to war, ignoring public opinion. Tony Blair and Gordon Brown decided that we would join George Bush in his invasion of Iraq, come what may – and the whole machinery of Government was bullied and warped to meet that end. This was not just a lamentable foreign policy decision – it was a failure of accountability and transparency at the very heart of our democratic system.

That is why the inquiry must focus on the political decision-making, not the military tactics. While it is essential that we find more and better ways of protecting our troops in conflict, and caring and supporting them and their families afterwards, there remains a danger that in setting up an inquiry the government will deflect attention from its own mistakes by focusing on military issues. That would be tantamount to an abandonment of the promised inquiry, and must not be allowed to happen.

Instead, the remit must focus on exactly how the case was made and presented for this war. From the question of how and why the Attorney General's legal advice changed, to how and why the expert intelligence was abused and politicised, the whole process from beginning to end must be drawn into the light and examined in detail. There can be no dark corners left unexamined.

Let me give an example of the questions the inquiry must answer: how close Iraq was to manufacturing nuclear weapons. Claims were made by Tony Blair, in the dossier and in Parliament that Saddam Hussein was between one and two years away from producing a nuclear weapon. But the intelligence said it would take five years.

This is just one of the distortions that needs to be explained. There are so many it would fill column after column if I were to outline them. But for every one, we need to understand: how did assessments by experts get so twisted? Who made these changes? And who agreed to them? What was a mistake? And what was a deliberate lie?

The people of Britain were duped by the government over Iraq. If we are ever to believe a government again in difficult times, the inquiry must get right to the heart of how this was allowed to happen, how government managed to overrule the experts and the truth. And changes must be made, safeguards introduced, to make sure nothing like this is ever allowed to happen again.

The author is leader of the Liberal Democrat Party