In the TES survey of teachers’ favourite fictional teachers which ran over the summer, neither of my top two choices gained a single vote. One of them was a fierce, fabricated, new deputy headteacher known only to staff and pupils at my previous school. The other is from a wonderful French novel, although my passive village teacher was never likely to spring to voters’ minds ahead of the popular creations of J K Rowling, Roald Dahl and co.

The invisible deputy, “Mr Carter”, was invented in a playful staffroom moment during a September Inset day. In their first lesson, several target classes were told about his arrival, about how he had been appointed because of his reputation in two key areas: discipline and extreme discipline. Not much else was revealed about him, the display of censorship suggesting that some things were better left unsaid.

The children’s imaginations then did the rest. Without ever meeting him they soon had vivid images of Mr Carter pacing around his room, keenly awaiting news of deviant behaviour. All was calm during his brief two-week tenure, after which he left owing to a never-disclosed “incident”. The boundaries had successfully been drawn.

My other favourite ran a boys’ boarding school in 1890s rural France in the classic novel The Lost Estate (Le Grand Meaulnes). Monsieur Seurel had none of the wit, charisma, weirdness or witchcraft displayed by many of the Top 50 nominations. But that’s exactly why I liked him.

Seurel understood that he was unlikely to be the most interesting personality in the classroom. Nor did he then make the mistake of responding to this fact by embarking on a career-long egotistical attempt to prove otherwise.

He similarly realised that many of his students would, at times, have a much more truly educational experience outside his classroom than inside it. When he learned that one of his students had ridden off on a horse and had not been seen for three days he did not trouble to tell the mother. When the boy finally returned, Seurel simply gave him a book to read and administered no punishment. He could see that the boy had been on some valuable journey of self-discovery.

Without Seurel’s laissez-faire approach, the lost student would never have chanced upon the dream-like party at a decaying country chateau, nor experienced a life-changing romantic encounter. The school gates (metaphorically at least, if not literally) should always be open for people sometimes to venture off, to get lost, to meet the unexpected. Nowadays such education may need a little more adult supervision and a lot more documentation, but we should still leave the gates open.

I also love this book’s depiction of village life and countryside in pre-First World War France, with its blacksmith, basket-maker and travelling players. Exactly 100 years ago this month its author, Alain-Fournier, was killed in the first weeks of the war at the age of 27. It was his only novel. There is perhaps no better time for people to read this story from a lost world.

Stephen Petty is head of humanities at Lord Williams’s School in Thame, Oxfordshire