Though it seems to begin as an affectionate memorial to his maternal grandparents, a testimonial to a rare and perfectly happy marriage, Their Promised Land by Ian Buruma has a deeper purpose. The cache of letters to and from Winifred (‘Win’) and Bernard (‘Bun’) Schlesinger is the pre-email, daily correspondence of two people who could not bear to be apart, yet were separated for years at a time by both world wars. Although his grandparents died in 1984 and 1986, this artful volume reveals a good deal about the world we live in today.

Born and brought up in posh Hampstead comfort, with plenty of servants, before moving to a spacious old vicarage in Berkshire, Win Regensburg and Bernard Schlesinger were ‘educated in the usual manner of the English upper-middle class: public school in his case, and Oxford and Cambridge,’ Buruma writes. ‘They were British and had the perfect right to insist on it, and yet their sense of belonging was never simply to be taken for granted.’

As you might guess from the names, they were Jews of German origin, but so assimilated that the high point of their year was their lavish Christmas celebration. They could have followed Win’s elder brother, Walter, who changed his name to Raeburn (and later exchanged his tepid Judaism for lukewarm Anglicanism); however, it was 1915, and as Buruma says, ‘the motive was not to get rid of a Jewish name, but of a German one.’

Was it the German-ness or the Jewish-ness of their names that prevented Bernard from obtaining the London teaching hospital appointments he merited, or from being sent to France after he enlisted; or Win, despite gaining her nursing certificate, from being accepted as a VAD in a Hampstead hospital? This sort of petty, but wounding discrimination carried on right through the second world war, when Bernard served with distinction, ending up in India. Whatever the cause of the couple feeling themselves not unreservedly English, it was not class — and this is one of the important themes of their grandson’s book.

Along with the money, the schooling, and the addresses of the upper-middles, Win and Bernard had something not always commonplace in this echelon of English society — access to, and a passion for high culture, especially music. They, and at least four of their five children, were accomplished musicians. The fifth was John Schlesinger, who gave up practising the piano for performing conjuring tricks, before making films such as Billy Liar, Midnight Cowboy and Sunday, Bloody Sunday. When Win and Bernard were young, the musical avant-garde was still Brahms (whom Bernard loved above all composers, except Noël Coward and, of course, Wagner). The omission of — say — Debussy, Ravel, Verdi and Puccini from Buruma’s index shows us that this culture was above all Germanic. Having such cultivated taste set them apart from many of their British peers (they were more like the Souls than the Bright Young Things), nearly as much as their totally non-religious (but hard to define) Jewishness.

They were probably more uncomfortable with (even non-religious) East End, Yiddish-speaking Jews like my own maternal grandparents than with the polite anti-Semites who thwarted their career ambitions. Win, in particular, sometimes found being Jewish awkward. In their correspondence, they used the number 45 to refer to Jews; and, when they, post-Kristallnacht, presciently and heroically brought over a dozen German Jewish children to London and safety, Win praised one of them for not looking very ‘45’. (The mysterious code remains unbroken.)

Buruma, brought up in the Netherlands, tells of his own shock when he first encountered casual British anti-Semitism, while doing a summer job in a firm of City solicitors in the 1960s: ‘It comes back to me every time I read about Win’s social cringes. She had to put up with something I never did.’ Yet they did not change their names and did not convert to any other religion (though their daughter, Hilary, ultimately became a Roman Catholic adherent of Opus Dei, says her nephew — without a hint of anything sinister). They were genuine patriots, loved England and adored Englishness —from the language, which they both wrote elegantly, to the landscape (Win was a gardener). In 1920 Bernard wrote to Win: ‘I tell the world… that I am by birth a Jew, a Jew still and proud of it too.’

Following its American publication (there are some barbarisms, such as ‘high tea’ for the ordinary meatless, sandwiches-and-cakes, late-afternoon repast; and a few otiose uses of the meaningless qualifier ‘rather’), there were the expected online review comments about ‘self-hating’ Jews. Yes, there were some problems in the lives of Buruma’s lovable, loving and captivatingly interesting grandparents, but not of their own making. The most important consequence of writing this exceptional book will be, let’s hope, that it kills off the cliché of the ‘self-hating Jew’, and makes it possible to talk — and think — sensibly about the hard question of Jewish identity.