The Second World War was the first Adventure in Time I wrote, and there's a story behind it. My son Arthur, then almost eight, was studying wartime evacuees at school, and we took him to the Imperial War Museum at half-term. I was looking in the shop for a book for him, couldn't find what I was after, and decided to write it myself.

The story begins with a disaffected boy in small-town Austria, who drops out of school, becomes a postcard painter and ends up as dictator of Germany. We meet the young Winston Churchill, the pilots of the Battle of Britain and the heroes of Dunkirk and D-Day. Anne Frank takes refuge in her Secret Annexe, while the besieged people of Leningrad gather to listen to Shostakovich's Seventh Symphony.

But there are plenty of lesser-known characters, too. A glamorous French secret agent called the Hedgehog, the codebreakers of Bletchley Park, a young man from Leicester who finds himself working on Burma's Death Railway, a Japanese teenager who survives the bombing of Hiroshima . . .

It's a very moving story, of course, but also a tremendously exciting one. I loved writing it.