Alex Deane is a partner at a City consultancy and a former Conservative Party aide.

With the news that Joe Biden will withdraw all American forces from Afghanistan by September this year, and the subsequent and inevitable decision by their allies that, without American air and other support, they would withdraw their troops too, the prospect of the Afghan government losing ground to the Taleban – and perhaps losing control to them completely – looms large in that country’s near future.

Twenty years is a long time to fight. One can understand all too well the frustration felt, on a bipartisan basis at the most senior level, with the fact that more progress has not been made, and the desire to end a conflict. Indeed, barring a very small amount of ongoing technical support, Britain withdrew our forces in 2014.

Nevertheless, to commit to withdrawal without preconditions and as an absolute (all out) rather than something less than that (leaving some troops behind as advisers; providing some form of anti-terrorism support; etc.) seems to render the potential collapse of democratic government, however imperfect, rather more likely.

A question arises from such a probability, much as it did for the Americans after the Vietnam War. What happens to those who were on your side? Who fought with you, worked for you?

To say that the prospects for “collaborating” Afghans under the Taleban are bleak seems an understatement so great as to be unworthy of the term. Whatever else was right or wrong about American involvement in Vietnam’s war, they acted with generosity, decency and honour when in 1975 they took in a great many who fled when the regime in the South fell.

I believe that such an obligation exists today towards for those who fought in Afghanistan in the long post-9/11 conflict – and that it applies to us in Britain as well as to others.

We should therefore prepare ourselves to take a significant number of Afghans fleeing their country in the aftermath of the withdrawal of allied forces in autumn this year. This should be in addition to any general quota for asylum seekers and refugees we intend to accept through UN programmes or other routes here.

The time must come, and it may come soon, when their lives become an awful lot worse. It may be because vengeance by others around them is visited upon them as the rule of law slides further in Afghanistan, or it may be because their country – in just two or three years, perhaps – falls to the Taleban or something like it, in its entirety.

Those who sided with us will face persecution, and, in many cases, death. So we should give them a new home.

I do not know how many will come, not least because the answer to the question of how many other countries in the changing coalition of forces that have served in Afghanistan will also act as we will and take a proportion of those concerned is unknown. But it will be many people. We should be ready for that.

There will doubtless be some predictable opposition:

“Not our problem” – If you feel this way, after what I’ve set out above, then I concede that I am unlikely to be able to convince you. But I suggest that it plainly is. Perhaps not to the same proportion or degree as others, principally the Americans, but we clearly have some responsibility.

“We’re busy” – Our economy has taken a significant coronavirus dip. But so has everyone else’s, and it is forecast to bounce back strongly – perhaps more strongly than anyone else’s.

As to being “busy” with those escaping unpleasant regimes to places with which they have strong links more specifically, I acknowledge that this call comes at the same time that the United Kingdom (rightly) gives new hope and a new home to those fleeing the Communists in Hong Kong. But discharging historic obligations is not a mutually exclusive pursuit. We are more than capable of honouring more than one tie at once.

“Who will come?” – The suspicion will exist that, hiding amongst those who take part in any exodus, will be those intending to do us harm, trained perhaps to pass themselves off as those who were our friends and not our enemies. As Mao said, the guerrilla must move amongst the people as a fish swims in the sea.

But there is an answer to this. Almost all can be vouched for by serving or retired military personnel, intelligence officers and administrators. Indeed, there might be an element of preference amongst those escaping to live amongst those with whom they worked – Britain might be thought to appeal more to those who fought alongside the British, America for those alongside the Americans, and so on.

“What if it’s fine in Afghanistan after all?” – That is possible, but not very probable. Aid alone is unlikely to achieve what aid and a sustained military presence could not, and aid is likely to be forthcoming in smaller amounts when troops are absent.

What constitutes “fine” is a live question, too. Many will choose, for many reasons, not to leave their country, no matter how bad it gets. It is their home. But some will wish to get out as things worsen. For many, by the time the danger is really clear it will be too late to save those who’ve been on our side and are now at risk from those we’ve opposed for so long.

“What will it cost?” – I don’t know. But whilst those who rallied to freedom’s call in Afghanistan were ordinary people hoping for a better country, they were also extraordinary. They were brave and they committed themselves to democracy and to us in the most visible ways. So I say that they will make the best possible migrants, bringing that spirit and bravery with them as they come.

I also suggest that this is a moral obligation that doesn’t come in pounds and pence. In any event, the cost is likely to constitute a fraction of the blood and treasure already spent upon the country for good reasons, and would have been all but guaranteed to have been spent if we had stayed the course with the Americans and the rest.

They fought with us. They stood by us and believed our promises about a better future and a better way of life. It’s time for us to stand by them.