In The Flying Classroom, set in a boys' grammar school, one of the pupils, Kreuzkamm, is captured by yobs from the school in town as he is carrying books through the streets. They burn the dictation exercise books and tie Kreuzkamm up in a cellar where they give him six slaps every ten minutes.

Naturally, the boys from the grammar school, led by our heroes Johnny, Martin, Matthias, Uli and Sebastian, triumphantly free Kreuzkamm and beat up the gang from town. Their victory is marred only by having to do the dictation test again in fresh exercise books.

But the torture scene in the cellar is unsettling. Anthea Bell, who has translated the Kästners for Pushkin, says: "You can see where the seeds of the concentration camps were sown."

The burning of the exercise books, too, is significant. The Flying Classroom was published only a few months before the night in the Opernplatz.

Kastner was twice arrested by the Gestapo for publishing political journalism and poems. After 1942, a complete ban was placed on his literary activities. His biographer, R.W. Last, writes that he "stubbornly continued working as far as possible and for as long as possible."

Anthea Bell calls the boys in The Flying Classroom a "bunch of right-thinking children". To English readers who have been brought up on Jennings, Just William and other boarding school books, the grammar school boys may at times seem more Fotherington-Thomas than Molesworth. They share their cakes, draw pictures for their parents, venerate their headmaster and cry when they are homesick. But they are saved from being treacly by also being ready to jump off ladders, duff up the bullies and suspend each other in buckets from the classroom ceiling.

What is striking about the children in all Kästner's books is their resourcefulness. When Emil has money stolen on the train to Berlin, he sets off in pursuit of the thief, recruiting a gang of boy detectives to help him. When Luise and Lotte in The Parent Trap (twice made into a Hollywood film, with Hayley Mills in 1961 and with Lindsay Lohan in 1998) meet at a summer camp and discover they are twins, separated when their parents divorced shortly after they were born, they swap identities and each return from holiday to the parent they have never met. Their ingenious switch reunites their parents, who marry for a second time.

The heroine and hero of Dot and Anton are particularly sympathetic characters. Anton's mother, who is recovering from an operation to remove a tumour, is too weak to go to work, so Anton goes out every night after he has done his homework to sell shoelaces and make enough money to buy sausages and potatoes for their supper.