Any book is a collaborative work, and I owe thanks to countless people – many of whom I don’t even know – who have played a part in making this story reach you.

Chief among these is my editor at HarperCollins, Nick Lake, whose thoughtful advice is always sound and helpful; also Samantha Stewart and Jane Tait, whose contributions are often disguised as small changes but which have a big impact. Thanks, too, to my brother Roy Welford for reading an early version and making valuable suggestions.

Last, but certainly not least, thank you to the booksellers, librarians, bloggers, teachers and others, for whose consistent support and recommendations I am hugely grateful.