EXACTLY 10 years ago today, the House of Commons was on the eve of arguably its most important debate in half a century or more.

I was one of the MPs who took part in that debate and the subsequent vote on whether UK forces should support US President George W Bush's invasion of Iraq.

The outcome of the vote and the basic facts of the invasion which followed are well enough known. However, a decade on, some of those facts and figures bear repetition.

The invasion and the carnage which flowed from it, principally in the form of internal sectarian bloodshed between rival Iraqi factions, is estimated to have cost the lives of up to 120,000 innocent civilians.

In addition, there have been almost 5,000 coalition military fatalities, including almost 200 military deaths among UK forces personnel. The Iraq war cost the Ministry of Defence more than £8 billion.

But the figures, raw and shocking as they are, cannot tell the full story of the horror, the human catastrophe, of the invasion and its aftermath, which endures to this day.

And, of course, there remains one other key statistic at the heart of the Iraq debacle: zero. For that is how many weapons of mass destruction were found despite the best efforts of Tony Blair, dodgy dossiers and all, to convince people that the Iraqi dictator was harbouring a stockpile of such weapons ready for use.

Blair used his Commons appearance in the key debate on the war to claim it was "palpably absurd" to suggest Saddam Hussein had unilaterally destroyed his (non-existent) WMDs. The palpable absurdity was Blair's – he took the UK into war on the basis of a gross deception and in contravention of international law.

The opinions of some of the most eminent figures in the field concur with that unavoidable conclusion.

Philippe Sands QC, a professor of international law at University College London, described the war as "wholly illegal", adding: "It wasn't justified on classical grounds of international law – self-defence wasn't even argued."

And former UN Secretary-General Kofi Annan said in 2004 that, from a United Nations Charter point of view, the war was illegal.

We still await the findings and report of the Chilcot inquiry into Britain's involvement in Iraq. However, thanks to the recent revelations by Sir Christopher Meyer, the UK ambassador to America at the time, we now know that Blair had agreed to support Bush's war plans – come what may – a whole year before the invasion. This damning account, backed up by the recollections of White House staff from the time, removes any lingering shadow of doubt that Blair's WMD claims were a ruse and that regime change, pure and simple, was the goal.

This week we have had a Conservative defence secretary coming north to lecture us on the defence capabilities of an independent Scotland. Leaving aside the effrontery involved, given Westminster's broken promises to Scotland on defence, it should be remembered that the Tories, with some honourable exceptions, backed Blair and Bush's war to the hilt and as such utterly failed in their duty as main opposition party at the time.

Our armed forces deserve enormous gratitude for the duties they perform, none more so than those who served in Iraq. But they were badly let down by the politicians, who breached the bond of trust our troops are entitled to expect from the political masters who send them into harm's way.

Tony Blair, it is said, spent his latter days in office fixated with the idea of his legacy and his place in history. He need not worry. His place in history is secure for all time.

The illegal invasion and war in Iraq is a disgrace without parallel in modern times, the shame of which will echo down the ages for Blair and all of those who were complicit in sending young men and women to risk their lives on the basis of a gigantic fraud.

And it is a deception which – I am absolutely certain – could and would not be perpetrated by the government of an independent Scotland, of whatever political persuasion.

Other countries, including Denmark, the Netherlands and Ireland, have constitutional guarantees that they will not go to war without explicit parliamentary approval, and a similar such undertaking could be written into the constitution of an independent Scotland.

Ten years ago, the Labour Party at Holyrood, under orders from their Downing Street masters, claimed that the Scottish Parliament was no place to debate the looming war.

A decade on and it would seem that they have learned nothing – only this week we had the ludicrous spectacle of Labour opposing the business motion at Holyrood, objecting to the Scottish Government's proposed debates next week on both Iraq and Trident.

They failed, thankfully, in their efforts to stop our national Parliament debating these hugely important issues. And on Tuesday I will be privileged to lead the debate on Iraq and to lay out the reasons why, a decade on, the lessons of the invasion remain more pertinent than ever.

By First Minister Alex Salmond