When Maxie Allen and Rosalind Levine posted complaints about their local primary school, they never expected six uniformed police officers to turn up at their door

Before it catapulted a small school community in London’s commuter belt into the centre of a global news story, the year-four class WhatsApp group at Cowley Hill school in Borehamwood was unremarkable – a place of snide comments, reminders about non-uniform day and flustered messages about being late for the school run.

“It was mum gossip, you know?” said one member, Sarah. “A bit juicy, but it wasn’t anything nasty.”

Sarah, who asked to use a pseudonym, is nervous about talking about the group, and little wonder. A conversation and controversy that started in the unofficial parent chat culminated in the arrest of two parents in the Hertfordshire town, sparking fierce debate about police overreach, the right to free speech and the relationship between schools and parents. The saga was covered around the world, discussed in parliament and drew the attention of Elon Musk on X, who appears to have viewed it as grounds for a “political revolution”.

In its own – thoroughly improbable – way, it raised a question that might feel familiar to many whose phones get overtaken by the school group chat: what’s the difference between a concerned parent, a busybody and someone who should face the full force of the law? Inevitably, it also featured a doorbell cam.