I jogged forward on the balls of my feet. If I could get close enough, I could probably swipe it. There was one seriously nervy moment when Dimples looked round. I was saved by a collection of mouldy cardboard boxes outside a door; I threw myself behind them, my heart hammering. When there was no shout or sound of feet thundering in my direction, I peered up. Dimples was blithely continuing on his way. Excellent.

When I got closer, I slowed my pace. One stretch of my arm and I’d be able to reach the backpack. I matched Dimples step for step so he wouldn’t realise anyone was right behind him and eyed the bag. It was beyond ridiculous that the Lia Saifire would be in there. Firstly, taking it on a stake-out would be stupid. Secondly, leaving it in an unlocked backpack in this neighbourhood was dumber than surfing on Ben Nevis. There was no way the jewel was in there. I should have turned back round immediately and got on with what I was supposed to be doing. My fingers were itchy, however. I just couldn’t help myself.

Pickpocketing is a hell of a lot easier than most people suppose. It just takes a delicate touch. Holding my breath, I reached forward and grabbed the edge of the zip, sliding it open two inches. Then I slipped my hand inside. My fingers brushed against something soft and velvet and I pulled it. Whatever it was, it was heavy. I pulled a bit harder, just as there was a sudden ring.

I froze, my hand still inside his backpack. He stopped, forcing me to stop as well, dug into his suit pocket and took out a shiny phone.

‘Yeah,’ he grunted.

I started tugging again, gently lifting the object towards the opening.

‘No sign of her. Byron’s going to be seriously pissed off.’

The velvet snagged on the edge of the zip. Shite, shite, shite. I was rusty. It had been a long time since I’d bothered with the sort of small ticket items you could get from this type of theft.

‘We should double back. She might go back home.’

Just as I thought I was going to have to use my teeth, I managed to free the fabric and pull away. In my hand was a small black velvet bag, tied with a gold string. Whatever was inside, it was going to be valuable. Even if it wasn’t the Lia Saifire, it was still satisfying. I carefully closed the zip again, something many pickpockets didn’t bother with. Taking the time – and the risk – to do it meant it would be longer before he noticed that anything was amiss.