‘In this instance, Sergeant? Yes, we do.’

He nodded. Sighed. ‘I was struggling somewhat with the aftermath of the Margetson killing. It brought the whole matter of my sister’s death back to me. I told Roz I was going to work. But I spent the day on the South Bank. Wandering around. People-watching. Relaxing. I needed some time to myself. And it was very therapeutic. Check the CCTV, if you’ve still got the footage on file. You’ll find me more than once. Wandering about, eating an ice cream, getting some sun.’ Before I got on a tube train north to go and meet a Polish delivery driver, he didn’t add. ‘You think that I was the Car Park Killer?’

‘It had crossed our minds. The machine pistol in question having been ballistically linked to several gang murders over several years. Clearly a weapon for hire. Possibly owned by Martin Hyde. And eventually surfacing in the possession of a recently deceased London gang boss by the name of Giuseppe Castagna. Known to his fellow criminals as Joe. Can you see where this is taking us?’

‘Not really. Gun dealers. Gang bosses. It all sounds a bit far-fetched to me.’

Mickey raised an eyebrow, inviting Irving to elaborate.

‘Two of the murderers who used that weapon have since been convicted. And, as you can imagine, they were both keen to provide any information that might contribute to their parole hearing’s outcome being favourable. They both told us they rented the MP5 from a man they contacted through the dark web. Going by the name of Steph. A man matching Martin Hyde’s description, it seems. And we’ve discovered that Hyde had an aunt who went by the name of Steph. Leading us to wonder if he was continuing an established family business.’

Mickey nodded. ‘OK, I can see the angle. You’re presuming that Martin, being from a long line of gun dealers, procured a weapon for me to murder Margetson with. And then lent me an MP5 that he rented out to criminals. Which I then used to attack the Castagna gang, having first established an alibi.’

And shut up again.

‘So, where were you at 16.00 on the day of the Car Park Massacre?’

Irving, boring in for the kill.

‘Just wandering about.’

True enough. And Mickey secure in the knowledge that when he stopped wandering about there was no CCTV of him ducking into London Bridge tube station. Thanks to a reversible jacket, a wide brimmed cricket hat and a quick image change in a camera-free section of Borough Market.

‘How did you get home?’

‘Taxi. I couldn’t face the tube. I paid cash.’

And there’s a dead end for you, he thought. You’ve got the weapon identified and that’s it. And was promptly proven wrong.