When the European migration crisis reached its latest peak earlier this year, a Jewish friend said to me: ''This will come round to hurt the Jews - you'll see.'' At the time, I dismissed it. ''The only group this might affect are Muslims,'' I replied. He knew better. ''You'll see," he warned. And now I have.

I've been writing about the migration crisis for a long time. It is a complex moral and strategic issue with few easy answers. But something is changing and, although I am not Jewish, I like to think I have been enough of a friend and developed enough of an understanding of the Jewish community in this country to be allowed to issue a warning of sorts.

The problem with the migration crisis is that the politicians are trying to follow public opinion, but the public do not know what we want. Do we want to be unprecedentedly generous or unprecedentedly fearful? Are the incomers like 1930s German Jews or are they just 21st-century economic migrants? Most of us think they are a bit of both and so our thoughts fluctuate. This makes the debate not only fractious but prone to dangerous swings.

In the summer, when the tragic photo came out of a young Syrian boy washed up on the shores of Turkey, some vocal Europeans had a spasm of ''let them in.'' Others said, ''be careful''. But the heart overruled the head. And can do again. The next turn of the wheel was always going to be when the migrants were associated not with humanitarian warmth but terrorist atrocities. Now they are.

How, then, could a migration of millions of Muslim men (in the main) from not only the Middle East but sub-Saharan Africa, have any negative effect on Jews? The first aspect is obvious: among those populations there will be many who bring the hatreds and suspicions of Jews that are inculcated in their homelands and faith. In time, this will lead to more attacks like that on the Jewish school in Toulouse (2012), the Jewish Museum in Brussels (2014) or the Jewish food-market in Paris (2015). But here, wider public sympathy will go to the victims of these attacks rather than their perpetrators.

This will come round to hurt the Jews, you will see

Yet another theme has bubbled up which it genuinely shocks me to discover. For many Jewish groups and Jewish leaders have been taking a conspicuous lead in welcoming refugees . Some initiatives – such as that to save Christian children in the Middle East who are being ''cleansed'' from the region – are hugely admirable and widely appreciated. But it is specific and needed. Other initiatives and statements from Jewish leaders and groups appear to be welcoming any and all refugees and equating the plight of 1930s Jews with all 21st-century migrants. This is not just a misreading of history but an incorrect application of history. It also sets up a dangerous linkage between Jews who are already in Europe and an increasingly unpopular, current European migration policy. Allow me to relay some recent personal anecdotes. They do not add up to an analysis but they are scents of something I believe is now in the wind.

During an episode of Question Time last month, the historian Simon Schama made a somewhat haughty and personal attack on my Spectator colleague Rod Liddle. Specifically, he chided Rod (who was urging wariness of letting into the country anybody who wants to come here) for allegedly turning his ''suburban face'' away from the troubles of the world. This was a little rich, and I said in print that it is all very well for Professor Schama to swan into Britain and tell us to take millions of migrants because he can always head back to his well-off (and distinctly white) neighbourhood in the US.

When the piece went viral, the replies included an element that was new and seized on an aspect of Schama that never occurred to me. ''One law for the Jews, another for the rest of us'' was the nub of it. Well, Schama is a distinguished public figure and can say and think what he likes. Nobody else needs to feel responsible for him.

A couple of weeks later, the Hungarian Prime Minister, Viktor Orban, got into a row with his country's most successful son. At a time when Orban was under huge pressure from his electorate not to let thousands of migrants into the country, he upbraided George Soros for being behind the many ''open borders'' NGOs which were putting pressure on Hungary. In reply, Soros confirmed that, yes, whereas Orban thought migrants the problem and borders the solution, Soros did indeed think borders the problem and migrants the solution.

In reporting this exchange, the same theme emerged. ''It's all very well for the Jews. They have Israel where only Jews can go and all the time they're destroying our own religious and racial identity in Europe.''

And another theme started to come up which I never thought I'd hear in my lifetime: ''Ah - the rootless, cosmopolitan Jew.'' Searching online I find that this is indeed becoming a theme. A video watched hundreds of thousands of times on YouTube excerpts an interview with a Jewish academic in Sweden who explains that Europe ''has not yet learned how to be multicultural.''

She goes on: ''Europe is not going to be the monolithic societies that they once were in the last century. Jews are going to be at the centre of that. It's a huge transformation for Europe to make. They are now going into a multicultural mode, and Jews will be resented because of our leading role.''

This remains a minority opinion for now. But here comes the bigger problem. Only seven per cent of Britons surveyed in a recent poll said they wanted immigration into Britain to increase. It is impossible to say what direction Europe is going to go in the near future, and we are all going to have to be on our guard and spend time countering bigotries and hatreds that could spill out in any direction. But the open-heartedness of so many Jews must also be countered by more vocal and visible even-headedness. In particular, this constitutes a careful warning that it could yet be a problem for European Jews if their leaders and visible figures get ahead of (and are seen to be the progenitors of) a mass movement of peoples that looks likely in the near future to go unimaginably sour, thus bearing out my pessimistic Jewish friend's worst fears.