Livre d'Or

The major Anglo-Jewish families kept a fairly strong insistence on marrying within the faith, meaning that everybody ended up multiply connected by marriage – this historical group is sometimes referred to as The Cousinhood.

I'd not come across that before; that's interesting.

These people mostly gravitated towards the major port cities, where there was a high demand for labour and housing was relatively cheap, so the East End of London, also Liverpool, Newcastle, Glasgow and so on.

I don't think it was so much that people gravitated there, as that they entered the country there and never got any further. (Consider, for instance, the relative size and importance of Greenock as a general community, and as a Jewish community one hundred years ago.)

Religiously these Europeans were often entirely secular, though a high proportion were Reform, the Reform movement being very much established in Germany.

Hmmm. There were a substantial number of refugees from Nazi Germany in Newcastle when I was growing up (and still some now), who were members of the Orthodox shul. I'd always assumed they'd always been Orthodox, but I find myself wondering now to what extent that was because there was no Reform shul in Newcastle at the time. Nevertheless, I do not get the impression that the Orthodox community in Germany had become moribund following the rise of the Reform.

These factors mean that it's more and more difficult for Orthodox communities to continue to exist other than in areas with high concentrations of Jewish populations, and this is a positive feedback system, because more and more people leave the small Jewish communities and move to the Jewish suburbs of big cities, making it even harder for provincial synagogues to survive.

I don't think that's why the Orthodox communities are dying in the provinces. The death of the provinces started in the early 1970s, long before the shift of your average Anglo-Orthodox person to the right. Anglo-Orthodox Joe at the time was "traditional", i.e. not observant enough to be bothered by the lack of an eruv and so on, and indeed many members of that generation (such as my parents) still are. By the time people started taking these things into consideration as to where to live, the provincial communities had already got into an irreversible spiral of decline.

Therefore any non-Orthodox rabbi's legitimacy can be questioned because at some point in the "chain" some rabbi is likely to have been ordained by a female rabbi, and therefore their rabbinical authority is not valid, and therefore anyone ordained by them isn't a real rabbi either. And anyone whose conversion is accepted by a non-valid rabbi isn't a valid Jew according to irritating divisive definitions.

I don't think this is why non-Orthodox conversions are not accepted by the Orthodox, or older Reform conversions would be accepted, or those by the UK Masorti community, which currently has a moratorium in place on female rabbis in public roles (I suspect this won't last the next decade, though). I think it's more simply a matter of rejecting the authority of a beth din which is prepared to make decisions (any) which run counter to Orthodox halacha.

Jewish schools, argh. When I was a kid nobody went to a Jewish school except maybe the most strictly Orthodox families.

That's not the impression I get from Londoners when I was growing up. And even in the provinces, I went to a Jewish school as far as Jewish schooling went in Newcastle (i.e. to the age of eight), and I was raised traditional, not Modern Orthodox.

But it's also to do with this utterly awful status anxiety; parents are more and more desperate for their kids to marry other Jews, not just any Jews, but Jews with completely impeccable Jewish status, because otherwise there's the chance that their grandkids or descendants will not be recognized as Jewish by the Israeli rabbinate and if the next Hitler comes along they won't be able to escape Europe and move to Israel.

That's not it, and you know that! The Law of Return does not operate according to the same criteria as recognition of Jewishness; if it did, you wouldn't have several hundred thousand non-halachically Jewish Soviet olim in Israel today!

the Orthodox movement is so hardline against inter-marriage or even marriage to non-Orthodox raised Jews who might have non-Orthodox converts in their ancestry.

Matrilineal ancestry, which is far less stringent a criterion. (I know you know this, but your readers don't necessarily.)

So [Jacobs] went on to found the Masorti movement

I don't think he did, actually: The movement arose despite him, rather than because of him. The shul he founded was independent, and so was its daughter shul. It wasn't until decades later that they affiliated with Masorti Olami; and Louis Jacobs himself continued, I think, to identify as Orthodox all his life.

the massive death rate of the younger generation in WW1

You think? Certainly in my family, and I suspect this would go for most Jews whose ancestors came over before the government slammed the gates of immigration shut in 1905, my ancestors hadn't all yet got British citizenship by WW1. I suspect those who died in WW1 were either from the old established, pre-1880s Anglo-Jewry, or were fighting on the side of the Central Powers, but whose family subsequently moved to the UK.