Lauren Child, author

Lola appeared to me in the flesh on a train from Copenhagen to Jutland. I was visiting my Danish boyfriend and we found ourselves sharing a carriage with a couple and their little girl, who kept bombarding them with questions while they were trying to read the paper. She looked like a pixie and, although she was clearly driving her parents to distraction, I found her mesmerising.

When I got home, I sketched a picture of her from memory and set about finding a story that suited her. My boyfriend had a younger sister called Sofie and, when I looked through family albums, I found she bore a resemblance to my pixie girl. So I drew on tales he told me about their childhood. While Sofie had adored him, he had found her intensely irritating, so she’d invented an imaginary “better brother” called Soren Lorensen. I named my character Lola, and Soren Lorensen became her invisible friend.

In those same family albums were pictures of my boyfriend in a T-shirt with different coloured sleeves and his name in flock. And so Charlie took shape. I’ve always been fascinated by how children talk: with my first book, Clarice Bean, I’d stopped trying to write in the way I’d been told to, and simply used the voice of a seven-year-old. This time, Lola’s voice came through to me very clearly and I borrowed from family memories of Sofie, who had her own jumbled words like “schooliform” for school uniform.

Children have a world you can’t enter as an adult. In it, small things can be unexpectedly significant. When I was young, I used to find going to other people’s houses very difficult because I liked food done in a certain way. Pies were especially troubling because you never knew what was in them. It was dreadful when I was given liver or steak and kidney pie because, in that era, you had to finish whatever was on your plate. My big sister, who could be Charlie-ish on good days, would wait till no one was looking, take my meat, and hide it in her hankie. I wanted to pick up on these tiny things that adults barely notice but that children can get so hung up on. Also, as a child, I’d often found myself alone with my friends or siblings, with no adult supervision. I realised that that rarely happens in children’s books: grownups are always making an appearance.