Gringo buried a fascinating link in the comments over at Maggie's, about the antisemitism of Germans, and the possibility that much of the refugee immigration was tolerated in order to get rid of Jews. It seems a stretch to think of this as a plot, but as a convenient development it is plausible.
The author is ex-leftist journalist Melanie Phillips. English, Oxford, my age, now more right-wing identified (though not on all issues). Worth a look, I think.