From the ruins of Mosul, from the defeat of Islamic State, there is a chance to build a lasting peace not just for Iraq but for the wider Middle East. This is no naive and optimistic boast, but a realistic assessment of the opportunity on offer. And Britain is uniquely placed to help make it happen. Here’s how we can go about it.

We need to realise, above all, that the rise of Al Qaeda in Iraq and then the Islamic State of Iraq and the Levant (Isil) was fuelled by the disfranchisement of Sunni muslims, who felt that Shia muslims, under the leadership of Shia Iran, grew too dominant after the demise of (Sunni) Saddam Hussein, so upsetting the regional balance of power.

The vast majority of Sunnis reject Isil extremism, but they ask themselves this question: why should we send our young men to fight and die stamping out Isil, only to put ourselves under the boot of Iran and Syrian dictator Bashar al-Assad, whose Alawite sect is also an offshoot of Shia Islam? They won’t do it. And when, as now, they see images of Shia militias, draped in religious flags, moving in to the ruins of Mosul to carry out vicious reprisal attacks on Sunnis, their resentment grows.

Such Shia revenge attacks must be stopped now. If not, Iraq should remember that Turkey, a nation of 80 million Sunnis, is on its northern border. Turkey’s increasingly despotic leader, Recep Tayip Erdogan, is itching for an excuse to move across the frontier. “Protecting” Iraq’s Sunnis would be the perfect cover.