A year or so ago the prison guards at Werrington Young Offenders’ Institution started hearing a new name circulating on the wings. Through snatched conversations between the inmates they could only make out the word “Cherub” and presumed with the weariness of experience that it was simply another gang on the rise.

On one level, they were right. Cherub relates to a group of orphans on the margins of society recruited for clandestine activities. But it was only after consulting the prison librarian that the guards discovered their true identity: Cherub was in fact the creation of author Robert Muchamore, whose books the prisoners – many of whom have long given up on their formal educations – have been devouring. Indeed for some, the 17-strong Cherub series, which have sold 13 million worldwide, are the first works of fiction they have ever read.

Muchamore, 43, is a world-famous writer of young adult fiction whom parents could be forgiven for knowing nothing about. He is the son of a Co-Op milkman and cleaning lady who grew up in a “scummy” part of Tufnell Park long before gentrification had begun to weave its course.