What makes a novel special? Obviously, it is a highly subjective exercise, but in Dennis Hamley’s latest novel, a chapter involving Elgar’s Cello Concerto does it for me. Divided Loyalties is about the impact of the Second World War on a family in England. German soldier Matthias and English nurse Ellen met in Hamley’s prequel about the First World War, Ellen’s People. They now have three children — Walter, who hates the fact he’s half-German, Paul and Anna.

The novel is chronological and each member of the family narrates a section as the war progresses. Paul tells of a family trip to Germany, pre-war, where cousin Helmut is introduced to Hitler at the Nuremburg rally. We are with Walter as he joins up as a soldier; Matthias when he is interned, first on the Isle of Man and then in Canada; and Ellen as she fights to get her husband released. The only voice heard outside the immediate family is Helmut, between 1943 and 1945. We see how he progresses from proud leader of his local Hitler Youth branch to disillusioned, exhausted soldier.

The final section is narrated by Anna. It is 1946 and as a music student she has been searching for something that condenses all the yearning and sadness caused by the war. When she hears a young Pole play the cello concerto, it encapsulates all those emotions perfectly. It’s one of those hair-tingling moments when you want to just rush off and listen to the music, because Dennis has described it so well. Then you realise that it won’t be the same, because the Pole won’t be pouring his soul into it, after the dreadful experiences he has gone through.

It is the moving climax to a book which has explained so well the motivations and thoughts of its characters. Although commissioned as a book for young adults, the complex themes in Divided Loyalties mean it should appeal to a much older readership, too. Meanwhile, the way Dennis uses different tenses and third or first person narrative for different characters gives the book an emotional immediacy, perhaps best exemplified by the cello concerto scene.

Dennis, who is 72, describes the Second World War as the shaping experience of his life. "I was three when it started, nine when it ended," he said. "Until I was nine or ten, I didn’t actually know what the word ‘peace’ meant. I thought that’s what people do, they have wars." He was ten before he saw a banana and remembers once seeing a Messerschmitt and Spitfire roaring over his Kent home. He thought it was a game.

When we met at his bright, airy flat in North Oxford, it is obvious he has pondered on what life would have been like if he’d not been brought up in England.

"If I was in Germany, an ordinary member of society, what would I have done? Would I have been strong enough to stand out and probably end up hung by piano wire? I don’t know. Would I have been an out-and-out supporter? I don’t know." He thinks it more likely that he would have been like the many millions in Germany who knew something was wrong and disagreed with it, but kept silent.

Best known as a children’s author, he has written 54 books, most of them while he was working as a teacher and then a teacher trainer. Although he had touched on war in a couple of these, it was with The War and Freddy, which is about a young boy’s experience of the Second World War, that he began to mine his own memories. In Divided Loyalties, there is less of his own experience, but he describes a real bombing raid involving his father at the airfield Biggin Hill.

Dennis moved from Hertford to North Oxford a couple of years ago after the death of his wife, to be nearer his daughter. The move has been very successful, partly because of his new partner Kay, an artist from New Zealand, whom he met on the towpath.

"Right out of the blue, finding myself with a partner, really put the icing on the cake," he said. "It’s nice to do what you like, but much nicer if you can do it with somebody else." Discovering Writers in Oxford, a social group for published writers, has also been a bright spot. "I think I flowered in Hertford, but here it lets me flourish much, much more," he explained.

Dennis believes that the 20th century lasted from 1914 until the end of the Cold War. "I think the main story was the huge European convulsion and that ended with the fall of the Berlin War."

He is now working on a third novel, taking some of the characters up to 1989. If it's anything like the first two, it will introduce another historical period in an engaging, thought-provoking way.

 Divided Loyalties is published by Walker at £6.99.