Then follows 15 minutes of paperwork – two sheets must be filled in on the details of the incident, before they are placed in an envelope, which itself must be filled in – and there is a rare period of calm and a chance to ask about the pressures of the job.

Carlson says it does get quiet like this sometimes, but he’s not complaining. “And at any point you can go from someone who’s had too much to drink to something like London Bridge.”

He was one of very first responders on the scene just after 10pm on 3 June – three minutes after the first 999 call – when three terrorists killed eight people and injured 48 with long knives around Borough Market. He was treating people while the attack was in progress after responding to what he thought was a normal call.

“That started as an RTA [road traffic accident]. I just thought it was a routine thing but then you get there and think, This doesn’t look like an RTA!

“I was there when the shots were being fired. I didn’t know if it was them or us. I was just around the corner from it.”

After six years in the profession, Carlson has trained himself to sleep after his 12-hour night shifts. It took a couple of years and the use of blackout blinds. He says he slept for 45 minutes that night.

Part of the appeal of the job is not knowing what might be around the corner. Carlson has delivered seven babies in his career so far, the most recent the week before we meet. “The human body just knows what to do,” he says. None of the women nor their babies needed hospital treatment.

There are currently 12 JRU paramedics in London, each attached to a single borough.

Despite its past reputation as run-down and crime-ridden, Carlson’s allocated area, Hackney, has reinvented itself through urban renewal to become one of London’s liveliest boroughs. Kingsland Road, the stretch running north to south from Dalston to Shoreditch, is now littered with bars, pubs, and clubs, as well as restaurants founded by Turkish and Vietnamese immigrants long before gentrification took hold, now enjoying a new lease of life.