When American and British-led forces invaded Iraq in 2003, neither George Bush nor Tony Blair, devout Christians both, can have imagined that one consequence of their action would be the extinction of Christianity in a land where it had survived for nearly 2,000 years.

Since Saddam Hussein's fall, perhaps half of Iraq's 800,000 Christians have fled the country. About half the rest are internally displaced persons. There is no mystery why. Last summer, the traditionally Christian Dora suburb of Baghdad was cleansed of its Christian families by threats, intimidation, looting and abduction for ransom. Even on the plains of Nineveh, where they now congregate, they have no effective protection.

So the temptation is to join the one to two million Iraqis who have fled to Syria, Jordan, Lebanon, Egypt and Turkey. Christians, who were less than 4 per cent of the population, now comprise 40 per cent of the refugees. The conditions they face are appalling - without work, subject to rackets, forced to pay for basic services, deprived of education, queueing for inadequate aid.

Iraqis of all religions share in the misery. But Christians and the other small religious minorities are in a special category, because the persecution they face is the result of their faith. The proof is simple: if they converted to Islam, as they are pressured to do, their prospects would be radically improved. But they refuse. So their leaders are martyred, their churches burnt, their legal rights trampled. Unlike Sunnis or Shias, Christians have no religious patron to protect them. All they have is us - or more precisely the Americans, since Britain has effectively retreated from military responsibilities.

But there are non-military responsibilities, and these the British Government should not be allowed to escape. Britain could and should radically increase aid to the Iraqi refugees - Christian and non-Christian - stranded in neighbouring countries. Above all, Britain should take in more Iraqi refugees, as Germany is doing, and give special priority to Christians, as France has promised to do.

Many of these people cannot and will not go back. The older, more tolerant, world they inhabited is gone, replaced by one where Islamic extremism is resurgent. Religion is one of the five criteria by which we officially judge a “well-founded fear of persecution”. Honest application of that criterion, and a willingness to explain the facts, would go some way to expiate the harm that we have allowed to occur in Iraq.

Robin Harris is consultant director of Politeia and a former prime ministerial adviser to Margaret Thatcher

Times Recommends

• A dose of defeat is just the medicine
• Protecting ourselves from Eurocreep
• After the summer of LUV, it'll still hurt