Facial recognition and spotters part of operation at Emirates that involved a dozen incidents and two arrests

The concourses are silent when, deep in the Emirates Stadium’s bowels, Chief Inspector Pete Dearden’s briefing begins. Arsenal’s 4.30pm kick-off against Chelsea is still hours away but the fixture carries significance as a London derby and because the Premier League champions are hosting a realistic challenger.

Dearden is a senior officer in the Metropolitan police’s public order command and Sunday’s matchday commander. He is, to borrow football jargon, giving the pre-match team talk, running through intelligence and in-game tactics. “Set the right style and tone,” he says. After Dearden has finished, the police room becomes a pseudo-station for the afternoon, with all incidents triaged by the same crime officer. Football offences can be found in niche legislation, and the Met wants London’s matchdays to be, so far as possible, policed uniformly.