Susan Sheehan won the Pulitzer Prize in general nonfiction for her book “Is There No Place on Earth for Me?”

When an author uncovers a ­half-century’s worth of hidden correspondence between his grandparents, a book is bound to follow. Ian Buruma found hundreds of letters written by his maternal grandparents in a stack of steel boxes in the barn of a house in Sussex, England. The letters belonged to Buruma’s uncle, John Schlesinger, the Oscar-winning director of “Midnight Cowboy.” Buruma used the letters in an earlier book, “Anglomania: A European Love Affair.” He has made them the centerpiece of his new book, “Their Promised Land: My Grandparents in Love and War.”

Buruma’s grandparents, Winifred Regensburg and Bernard Schlesinger, came from “solidly middle class” families who had immigrated from Germany to England in the late 19th century. They were Jews who prospered in business in England, with both their fathers succeeding as stockbrokers in London. They settled in Hampstead, London’s haute bourgeoisie Jewish section, and their children were brought up speaking English and loving England. Buruma chronicles the 10 years from the time Win and Bernard met to the time they were able to marry, in January 1925, after he served as a stretcher-bearer during World War I and completed his studies to become a pediatrician.

Bernard tells us little about his war service in the trenches around the Somme, because of the horrors he witnessed. He reenlists in World War II, but his observations about his postings to places like India aren’t especially insightful or colorful. And the couple’s exchanges about their cultural exploits — concerts they attended, or the small orchestras or chamber-music groups in which Win, a proficient violinist, played — are of little interest to anyone beyond their authors.

’Their Promised Land: My Grandparents in Love and War’ by Ian Buruma (Penguin)

As for their love and marriage, John, their first child, was born in 1926; Buruma’s mother, Wendy, was born a year later. The twins, Roger and Hilary (the latter of whom converted to Catholicism and became a member of Opus Dei), followed in 1929. Susan, the fifth and last child, was born in 1933, became an actress and committed suicide at age 30. In 1940, Win wrote to Bernard, “I love my mother & my brother & sister & my large flock of children, but none of them mean to me what you do, who after all these many years are still my dear, devoted love.” About this, Buruma comments, “For Win, at any rate the safest shelter was always their island of two.” For Bernard, the marriage was also the core of their private world.

But ignore the subtitle of the book! “Their Promised Land,” though styled like a scrapbook, with family photos and letter excerpts, is not at heart a tale of love and war. Its true subject — and it is compelling — is assimilation and anti-Semitism.

While Win and Bernard never converted to Christianity, they embraced secular Christian experiences such as the celebration of Christmas. Buruma, born in 1951 in the Hague to Wendy Schlesinger and Leo Buruma (who was from a Protestant family), begins his book with a description of his grandparents’ over-the-top holiday festivities:

“Everything about Christmas seemed . . . more lavish than anything we were used to at home in Holland — the mistletoe, the ubiquitous holly, the candles, and especially, in the large drawing room looking out onto the garden, the Christmas tree, whose opulence, like so much else, might be slightly magnified by memory, but not much. Dripping with gold and silver baubles, festooned with streams of glittery trimmings, angels dangling from pretty little candlesticks, the tree was topped by a shining angel stretching her arms all the way to the high ceiling. This totem of pagan abundance, looking over a small mountain range of beautifully wrapped presents at its base, was not really vulgar — Granny had excellent taste. It was just very, very big. The impression was clear: here was a family that was serious about Christmas.”

The Schlesingers were not immune from treating with disdain Jews they regarded as belonging to a lower caste. An example, also mentioned in “Anglomania”: After joining the Queens Westminster Rifles, Bernard hoped to share his billet with a friend from school named Sharp but was instead billeted with another friend named Cohen, and worried that this man was “too Coheny.” Buruma writes that this perspective was “a matter of class.”

It is curious behavior, especially since Regensburg and Schlesinger themselves suffered discrimination based on their names. Win was turned down for a volunteer job during World War I at a hospital. She was accepted as a volunteer at Beech House, a hospital entirely staffed by Jews. In 1938, after Bernard failed to procure a position at St. Thomas’ Hospital in London, he blamed it on “45” — the family code meaning Jewish — “the old, old story.”

The Schlesingers’ most virtuous deed resulted from that snub. Some months before the Kindertransport was launched in 1938, Win and Bernard decided to take in 12 Jewish children from Germany. “Failing to get into St. Thomas’s had a share in that,” Bernard wrote. They requested children “specially chosen from the professional classes about whom we have either personal or reliable knowledge.” Or as Buruma observes, they selected “children from families much like their own,” children who would “fit in.” These children initially lived in a hostel set up by Win and Bernard in North London until they were sent to various schools around England. One of the selected 12, Vera Baer, wrote to Win in 1943, enclosing, in Win’s words, “a charming little photograph of herself.” Win continues: “She has grown into a very pretty young girl, without a trace of 45 or German.” Whereupon the author adds: “Without a trace of 45? This was more than Win could say of herself, or indeed any of her kin. More than once, she frets about my mother Wendy’s perfectly respectable Jewish nose. A minimum of 45, combined with a thorough ‘de-Germanization,’ was clearly necessary to gain her approval.”

Buruma ends his book with a visit to the modest graves of Win, Bernard and John Schlesinger in the United Synagogue Cemetery in Willesden, now an ethnically diverse area of northwest London. He does not expect the reader of their letters to love Bernard and Win, as he did, but he hopes to have honored their memories. Perhaps he has.

Their Promised Land
My Grandparents in Love and War

By Ian Buruma

Penguin Press. 305 pp. $27