The longer I pondered how to start this profile, the greater my perplexity grew. For the Jews in Britain are anything but homogeneous, and it felt impertinent, indeed wrong, for a non-Jew to impart a spurious unity to the subject, or to brush aside intractable problems of definition.

As Gideon Rachman protested in this week’s Financial Times,

“Identity politics is fundamentally illiberal because it imposes a group identity on individuals. Like most people I know, I have a composite identity. I am Jewish. I am also British, a Londoner, a journalist and a history graduate. I am married to a non-Jew who shares my indifference to religion.”

But Jeremy Corbyn has compelled a discussion of Britain’s Jews. For as anyone who was present at last week’s demonstration in Parliament Square will confirm, he has inflicted grievous pain on Jewish members of the Labour Party, by associating himself so closely with anti-semitic groups.

Although I sketched that demonstration, which was organised by the Board of Deputies of British Jews and the Jewish Leadership Council, I realised afterwards that I had failed to convey how British the whole occasion felt – as British as a cartoon by Pont. Here was a group of British citizens whose patience had been tried beyond endurance and were in a state of agony, but who trusted in the power of peaceful protest, organised at short notice and in a pleasantly makeshift way, to make things right.

The Board of Deputies was founded in London in 1760. Jews had arrived in England under William the Conqueror, were subjected to vicious attacks including the massacre in York in the reign of Richard the Lionheart, were expelled in 1290 by Edward I, and were readmitted in the 1650s by Oliver Cromwell.

This new, relatively small population of Sephardic Jews from Spain and Portugal founded Bevis Marks Synagogue in the City of London, and in some cases rose to eminence. Luckily for Benjamin Disraeli, his father, Isaac, who was actually the son of an Italian Jew, fell out with that synagogue, which tried to fine him £40 for refusing to take up the office of Warden.

Isaac resigned from the synagogue and in 1817 had Benjamin baptised, at the age of 12, into the Church of England. But for this, Disraeli’s brilliant political career, culminating in the leadership of the Conservative Party and the prime ministership, would have been impossible, for until 1858 practising Jews were debarred from becoming MPs.

Not that Disraeli was inclined to downplay his origins. He always regarded himself as Jewish, and was immensely proud of his ancestry, which he insisted made him as aristocratic as any Englishman: “I am not disposed for a moment to admit that my pedigree is not as good as that of the Cavendishes [the Duke of Devonshire’s family],” as he put it when standing for election against one of them.

Disraeli was an exotic figure, yet was also assimilated into the English ruling class, and displayed a remarkable ability to charm Queen Victoria, a task quite beyond his mighty rival, William Gladstone.

After his death on 19 April 1881, Disraeli became the only former prime minister to have a monument erected to him by a reigning sovereign, and the only one to become the inspiration for a vast voluntary organisation, the Primrose League, which each year laid primroses at his statue in Parliament Square.

There has not yet been a second prime minister of Jewish descent, but from the 1890s there was a second, much larger wave of Jewish immigration, of an entirely different nature to the first. For these were poor, uneducated Jews fleeing from pogroms in Russia and other parts of eastern Europe, who lived in cramped conditions in the East End of London.

They brought with them a work ethic, and a sense of family and community, which enabled their descendants to prosper, and to move to more commodious districts in north London. In the late 1930s, a third wave of highly educated Jewish immigrants arrived, fleeing Nazi persecution, many of whom carved out distinguished careers.

According to a report produced in 2016 by the Institute of Jewish Policy Research, on behalf of the Board of Deputies, there are now 454 synagogues in the UK, the largest number ever, but there has been a decline in recent decades, and probably since the 1950s, of synagogue membership numbers, which now stand at below 80,000 households:

“However, the overall decline masks important developments at a denominational level. Critically, the sector that has declined most sharply is central Orthodoxy – broadly understood as the United Synagogue, the Federation and various independent modern Orthodox synagogues dotted around the country – which collectively have seen a 37 per cent drop since 1990. This decline is partly due to disaffection, but it has also been driven considerably by natural decrease – more members dying than being born.

“In contrast, membership of strictly Orthodox synagogues is growing. Indeed, it has grown dramatically over time – by 139 per cent since 1990. A generation ago, the strictly Orthodox comprised 4.5 per cent of all synagogue members households; today they comprise 13.5 per cent. This growth is driven almost exclusively by demographic forces – particularly, high birth rates in this sector of the community.

“Taken as a whole, Liberal, Reform and Masorti figures have been fairly stable over time. Liberal and Reform have both declined slightly since 1990, whereas Masorti has grown, albeit from a lower base. But this overall picture of stability is somewhat misleading: in reality, Liberal and Reform synagogues are both losing members at a similar rate to the central Orthodox ones, but unlike those central Orthodox ones, they are also attracting members from their religious ‘right’ to offset those losses.”

Population projections seldom turn out to be correct. But were the strictly Orthodox Jews in districts such as Stamford Hill to continue to increase at their present rate, they would by 2050 constitute a majority of British Jews. They are notable for their social conservatism, which leads them to preserve the dress (black hat and long black coat), languages, sabbath and dietary observances their forebears brought with them from Europe.

As one of them told me when I visited them in the early years of this century, “The hats we wear were fashionable 100 years ago. The Jews had to keep up with the fashion. We stay with what we came with from Poland. That’s why you see different hats. The flat hat is from Hungary, the tall hat is from Poland, you have the one that is plain material from Russian Poland and the west European Jews go with one that is bent down at the front.”

The schools of these strictly Orthodox Jews are independent from the state system, and are named after towns and rabbinical dynasties in Poland, Russia, Romania and Hungary. Boys and girls are educated separately.

At a school I visited, 15 rabbis, or teachers, were giving instruction to 250 boys. I saw a lively class of 11-year-olds, wearing skull caps and sidelocks, learning the scriptures in Hebrew and Aramaic from their rabbi, with Yiddish as the medium of instruction. At the end of the day the boys did an hour of English and maths. 

The modern world, with its insistence on the equal respect to be accorded to transgender people and to same-sex relationships, is firmly excluded from these schools, which leave sex education to parents, who in turn regard it as preparation for marriages in which contraception is seldom employed, and which on average produce about eight children.

Ofsted is not amused by this rejection of modern norms, and is anxious to be seen to take as hard a line with Jews as with Muslims who uphold pre-modern standards, so trouble can be expected. The irony is that there is no evidence of socially conservative faith schools, Jewish, Muslim or Christian, producing terrorists. There the internet, a quintessentially modern form of communication, plays a greater role, and finds its easiest victims among those who have received no proper introduction to one of the great traditions.

I hope this excursion into Stamford Hill, so untypical of widerJewish society, at least helps demonstrate the truth of the assertion at the start of this profile that Britain’s Jews are not homogeneous. At the other end of the scale can be found many Jews who marry out of the faith, and become difficult to classify or to count, for they have become assimilated into secular, liberal-minded society.

And in the middle are perhaps a quarter of a million British Jews who are still observant, and are, among other characteristics, intensely patriotic. They toast the Queen, and pray for her, before they toast the President of Israel. For as the descendants of immigrants who fled persecution, they are deeply grateful to Britain, while also knowing that Jewish history demonstrates the advisability of keeping some final place of refuge.

Although there have long been Jewish MPs in both the Labour and the Conservative parties, there is no doubt that the former at first made the greatest appeal to Jewish voters. Only when Margaret Thatcher became Conservative leader and Prime Minister did the balance shift.

For she gave ministerial posts to many Conservatives of Jewish descent, including Keith Joseph, Leon Brittan, Nigel Lawson, Malcolm Rifkind and David Young. Labour also had eminent Jewish or partly Jewish figures, including Joel Barnett, Peter Mandelson, Margaret Hodge, David Miliband and Ed Miliband, and Tony Blair relied heavily on his gifted friend Michael (later Lord) Levy to raise the funds which would free him from excessive reliance on the trade unions.

But a later Labour leader, Ed Miliband, ran into severe difficulties by seeming too inclined to support the Palestinians against Israel, and by simply not understanding what note to strike when addressing Jewish audiences.

David Cameron suffered no such difficulty. His speech delivered to the Jewish Care Dinner on Monday 21 June 2016, so only three days before the EU referendum, shows the uninhibited manner in which he campaigned, successfully, for Jewish support:

“I want to say some very simple things tonight. The first thing is that I love you. I love Jewish Care and what you do. So much of what you do epitomises what I’m getting at when I talk about the Big Society.

“Whether it’s your army of 3,000 volunteers, the 12,000 kosher meals on wheels you provide, your pioneering wrap-around care, you don’t just leave things to the Government, you get up, you make a difference, you serve your communities, you help others, you bring people together to play their part, and that is the Big Society, Jewish Care in action.”

Theresa May, though in theory on the side of British Jews, has not yet shown them that level of love, so cannot – despite Corbyn’s faults – be so assured of their support.

And yet it is arguable that not only Cameron’s narrow victory in 2015, but her ability to carry on in 2017, were attributable to Jewish votes. For Britain’s Jews are geographically concentrated, with about two-thirds of them either in London or in the parts of Essex and Hertfordshire next to London, while there are other sizeable communities in Manchester, Leeds, Gateshead, Glasgow and Liverpool.

Some Conservatives believe that in 2017 the party only held (with the majority given in brackets) Finchley and Golders Green (1,657), Hendon (1,072), Chipping Barnet (353), Harrow East (1,757) and East Renfrewshire (4,712) – the latter containing about 4,000 of the 5,000 Jews in Scotland – with the help of Jewish voters. And without those five seats, a deal with the DUP would not have been feasible.

Sadiq Khan, the Mayor of London, attended a Jewish event “every other day” during his campaign in order to dispel the doubts which, as a Muslim, he aroused among Jews. As one Jewish observer puts it, “He had to do a lot of work winning the trust of the Jewish community, and it paid off.”

Ken Livingstone, the last Labour Mayor of London, tried to divide and rule among the city’s minorities, and for a time this worked for him. But in the end, he came to be seen as such a horrible and divisive figure that he was beaten, twice, by Boris Johnson, against whom in those pre-referendum days it was very difficult to stir up hatred,

My guess is that Corbyn’s sympathy with anti-semitic groups will arouse more disgust than admiration among London voters, but we shall see. The borough of Barnet, which has the highest proportion of Jewish voters in the country, will be a key test in the forthcoming local elections.

But the Jewish contribution to Britain should not be reduced to mere political calculation. Here are great scientists, philosophers, theologians, historians, writers, journalists, bankers, retailers, lawyers, doctors, social scientists, actors and philanthropists.