It struck me that formally interviewing him again wouldn’t get us any further. But that didn’t mean he shouldn’t remain a prime suspect along with Slack himself. And if so then there had to be a way to find out what he really knew. A way to prove that The Rottweiler was lying through his fucking canine teeth.

But right now I couldn’t see a way – not unless we followed Tony Marsden’s example and broke all the rules in the book.

The news from Peckham was worse than bad. It came through at two o’clock in a phone call from DCS Drummond that was put on speaker so that we could all listen in.

‘This is a fucking clusterfuck,’ he seethed. ‘DS Marsden has been arrested along with two of his pals from Wandsworth CID and another who’s attached to the firearms unit. They took Slack to a car mechanic’s workshop with the aim of torturing a confession out of him. Luckily the response team arrived before they got down to the heavy stuff, but he was roughed up and is at the hospital. And before anyone asks, no, he didn’t confess to anything. He continued to deny being responsible for what’s going on.’

This wasn’t what any of us wanted to hear. When the news got out it was going to be a public relations disaster for the Met. It wouldn’t matter that Marsden and his crew had acted out of desperation following the Commissioner’s murder. They had broken the law in a big way and had brought disgrace on themselves and the rest of us.

It wouldn’t have been so terrible if they’d got him to fess up. They’d still be in trouble but it would have been worth it. Now, though, everyone lost out.

There was going to be enormous pressure to leave Slack alone. And valuable time and effort was going to be wasted pursuing other suspects while Slack’s hired gun continued her merciless killing spree.

There was a mixed reaction in the office. Some of the detectives condemned Marsden’s actions, including Janet Dean, who said there was no excuse for what he’d done.

’It’s not our job to act as judge and jury,’ she said. ‘The prick has shamed us all.’

The discussion also triggered speculation as to who had betrayed him. And once again Janet’s reaction to what he’d done got me wondering if it was her. Was she the person who had given Slack all our personal details? The bent copper who was obviously working for the gang boss?