Perhaps public attitudes to immigration are relaxing, now we have control of our own borders: it may be that the change in itself has restored voter confidence.

Or it could be that many voters differentiate Hong Kongers from other migrants – viewing them as family-focused, hard-working, law-abiding and, above all, as spotential and real victims of a totalitarian regime, China.

There is some evidence for both claims.  Migration Observatory cites the British Election Survey, Ipsos MORI and the European Social Survey in claiming that the public’s views “appear to have softened in recent years”.

And according to YouGov, no less than 64 per cent of its poll respondents approve of the Government’s plans for people from Hong Kong – a total that rises to 85 per cent in this site’s own survey.

But there is also reason for caution.  Both Migration Observatory and MigrationWatch agree that a plurality if not a majority of voters want immigration levels reduced: they cite figures of  44 per cent and 60 per cent respectively.

Furthermore, YouGov suggests that public awareness of Ministers’ plans is relatively low, arguing that “it is possible that the Covid-19 pandemic has distracted the public’s attention”.

We sound this warning note a week after Robert Jenrick’s article on this site, setting out the Government’s “initial £43 million package to help new arrivals find a home, a school place for their children, employment or a route to set up a business”.

The Housing Secretary was absolutely right to wish those who have arrived “the very warmest of welcomes”.  “Our message is clear,” he added, that “the UK government and the British people are here to welcome you with open arms”.

And it is undoubtedly true that nowhere near the near five and a half million Hong Kongers eligible for the Government’s pathway to British citizenship are likely to come to the United Kingdom – let alone at once.

Indeed, the aim of Government policy is to encourage the opposite: by giving these Hong Kongers an exit route over time, they hope to quell any immediate mass flight for Britain.

The policy also sends a signal to China: don’t think that you can crack down on the rights and liberties of the people of Hong Kong without consequences.  They can always leave – taking their wealth and talent with them.

Ministers are essentially taking the same gambit as their Conservative predecessors did in 1989, when the then Conservative Government granted British citizenship to some 250,000 Hong Kongers.

However, what will happen if they bungle their calculations, as Labour did over people from Eastern Europe after EU enlargement during the early 2000s?

The Home Office’s central estimate is that nearly 300,000 Hong Kongers will take up the new visa route over the next five years: the real total could be lower…or higher.

The former chair of the Migration Advisory Committee, Alan Manning, has sounded a warning note. “In particular, in this case, how the political situation in Hong Kong is going to evolve, over which the U.K. has very little power,” he has said.

“The very big numbers are really what you would get if there is absolute meltdown and anarchy in Hong Kong. That’s really in the hands of the Chinese government.”

Our take is that an emergency influx of tens and thousands of Hong Kongers at once would both raise the salience of immigration policy in general, and be felt in some parts of Britain more than others, as immigration was during the run-up to the 2010 general election.

To be clear: this would be nothing much to do with “race”, or even with the abstruse debate about whether migrants create more wealth for the country than they consume.

The controversy, as so often before, would be concentrated on particular pressure in particular places: on schools, hospitals, road, rail, other public services and, above all, housing.

If there were a significant arrival of Hong Kongers during the next few years (unlikely), and Boris Johnson was still in place as Prime Minister (likely), it would take place against the background of a quiet shift to a more permissive migration policy.

That’s what we called Charlotte Gill’s recent piece on this site explaining some of the Government’s post-Brexit plans, such as the scrapping of the net immigration target and the reduction of the minimum salary threshold.

The changes reflect Johnson’s liberal instincts on migration: as Mayor of London, he favoured an amnesty for illegals, and has floated the idea again recently.

His actual views and policies are therefore solid evidence against the inflammatory charge, made by some of his more committed critics, that he is, as one of them put it, “a modern-day Enoch Powell”.

Nonetheless, they are vulnerable in the event of a sudden change of public mood about migration levels.  Last year’s figures showed net migration from outside the EU hitting its highest levels for 45 years.

These were offset by a steady fall in the number of people arriving from EU countries for work: in total, more than 677,000 people moved to the UK and about 407,000 people left, according to the Office for National Statistics, which said numbers overall are “broadly stable”.

We are where we are – but it is surprising, on the face of it, that the Government didn’t push instead, or in parallel, for a more international-flavoured distribution.

After all, some of those 4.5 million people eligible for the pathway to full citizenship might prefer to migrate to Taiwan or America (Hong Kongers are already moving to the former in record numbers).

The site is especially struck by the silence, as far as we can tell, from the Conservative backbenches.  No Tory MP that we’re aware of has followed Andrew Green of MigrationWatch, campaigning against the Government’s plans as irresponsible.

Perhaps those Conservative backbenchers are reading the public mood and international situation correctly.  Or maybe the way in which politics is practised has changed.

It could be that it is now predominately carried out in Twitter rather than broadsheet style: in other words, what matters is to meet the needs of the moment, rather than plan for the problems of the future – or possible ones, at any rate.

To some extent, this has always been true, but our sense is that there is more short attention-spanned government than there was: the imposition of tougher climate change targets that no-one seems to have a clue how to meet is another pressing example.

At any rate, we hope that this policy works out well for all concerned.  But there must be space in the public square for someone to point out that it may not.