There were five television monitors in the room and it was hard to ignore the footage that appeared. There were shots of the Prentiss house, the uniforms and forensic suits gathered in front of it. There were also several shots of Dave Prentiss and constant references to the fact that his wife had only just given birth.

‘Scotland Yard is saying very little at this stage,’ the Sky News presenter said. ‘But there are reports that Detective Inspector Prentiss and other officers attached to the organised crime task force had received anonymous text messages containing death threats. We’ll bring you more as and when we get it.’

As the morning progressed I kept thinking that I would wake up from a terrible nightmare. But it wasn’t to be.

As dawn broke over London I was convinced that the new day was going to bring more pain and heartache.

At six o’clock in the morning I had the dubious pleasure of interviewing Roy Slack again. He was amongst a bunch of high-profile villains who were rounded up across London overnight.

They included members of gangs that were on the task force’s target list and individuals who fitted the profile of a contract killer. Their names were provided by the Met’s Intelligence Unit and it was surprising how many there were and how many I’d never heard of.

Among them were those suspected of gang-related murders, those who’d served time for gun crimes, and former soldiers and mercenaries who had made names for themselves in the underworld.

One name stood out. Danny Carver. The Rottweiler. He was being questioned by officers at Streatham who had descended on his house in the early hours.

His boss had a lawyer with him this time – a fat, sweaty man named Darren Peacock – and the process was much more formal. We were in an interview room and Kate Chappell and I were facing Slack and Peacock across a table. The interview was being recorded and Slack had been read his rights.

We were late getting started because Peacock had only just turned up and he clearly wasn’t happy about being dragged out of bed.

‘I would like to state at the outset that I shall be lodging a formal complaint on behalf of my client,’ Peacock said. ‘It’s clear he’s the victim of an extreme case of police harassment. This is the third time in a week that he’s been questioned. And it was totally out of order to wrench him from his bed at four o’clock in the morning.’