Prime Ministers come and Prime Ministers go. This was my sixth leadership battle, and it has been even more bloody and unpredictable than any since the loss of Margaret Thatcher. The Conservative Party has its way of doing these things, which is the envy of Labour!

I supported Andrea Leadsom, but she did the right and honourable thing by standing down in favour of Theresa May. We will have a new PM in place within three weeks of the Referendum, and the ship of state can steady itself and prepare for the Brexit negotiations to come. Theresa is a very safe pair of hands.

The Chilcot Report was a long-time-coming, but it was well worth waiting for. Those who had confidently predicted a ‘whitewash’ were thoroughly disappointed, as were those seeking a witch-hunt scapegoating of certain individuals.

It is a well-balanced, carefully argued and evidenced analysis of what went wrong in 2003 – the decision-making; the conduct of the war; and our complete failure to plan for the post-conflict reconstruction of Iraq, for which we will pay a full and heavy price for many years to come.

Tony Blair’s informal sofa-style Government; his slavish subservience to President Bush; his obsession with ‘spin’ and ‘presentation’ at the expense of substance and veracity took us into what was clearly, in my view, an illegal war.

It is true that Chilcot did not quite say so, not least because it was beyond his remit. But I am glad that I resigned as Shadow Defence Minister over what was, in my view, a deeply flawed decision.

I will, however, always kick myself that I was persuaded by the whips to abstain in the vote on the war rather than vote against the Government.

Incidentally, one outcome seems to me plain: that a vote in the House of Commons on war by no means guarantees that it is legal or justifiable. Indeed, as I argued in my book Who Takes Britain to War? by whipping MPs into supporting a war you are by that very means removing their right and ability to challenge the government on it. Rather than empowerment, a Parliamentary vote could become emasculation.

I remember visiting the front line in Iraq in 2003 shortly after the invasion, and being struck by the inadequacies of some elements of our troops’ equipment, at least partly as a result of the very short lead-in time which Mr Blair’s shenanigans gave them. Several of the bodies so sadly repatriated through Royal Wootton Bassett High Street were needless deaths caused by the inadequacy of certain equipment. That lesson must be firmly learned by the MoD.

Tony Blair, Jack Straw, John Prescott and the others who were responsible for the war will carry a heavy burden of doubt with them to their graves. But rather than revenge, we should now seek to use the consequences of Chilcot to make sure that anything similar can never happen again. We need to have better and clearer procedures for deciding on expeditionary warfare; we need to be ready to conduct it more professionally; and we need to plan better for its aftermath.

Sir John Chilcot will have done the world a great service if we politicians will but heed his conclusions. I am confident that Theresa May will do so.