Traditionally, the weapon of choice for a classically trained wizard is the fireball – I’m not kidding. And in some respects, from a policing point of view, it’s not a bad weapon. Being by definition a soft and low velocity projectile, you can loose them off in the knowledge that it’s not going to blast through your target, the wall behind them and the bus queue of blameless OAPs behind that. However, this means that – unless you’re Nightingale – the bloody things can be stopped by modern ballistic armour, my metvest and, in some cases, a thick woolly jumper. At the same time, they remain potentially lethal, which means you’ve got to be careful who you lob them at.

So I water bombed Lesley instead.

It’s a harder spell, third order, based on two formae – aqua, impello – and a couple of extras we call adjectivium which modify the way other formae work. The result generates a ball of water the size of a party balloon which, when properly applied to a suspect’s face, often causes them to cease and desist in their activities – whatever these might be. Fireballs are much simpler and easier to cast under pressure, but I’d been practising the water spell by playing dodgeball with one of Beverley’s younger sisters and, trust me, if you do that with a hyperactive nine year old river goddess then you pick up the skills fast.

Nightingale says that one of the prefects at his old school claimed there was a variation that created a ball of gin, but try as they might nobody ever found the spell or worked out how to recreate it.

‘And, as you can imagine,’ Nightingale told me, ‘a great deal of effort was expended in that direction by the sixth form.’

Water was fine for my purposes, and I’m sure Lesley appreciated the elegance of my approach when it smacked her in the face. She went down swearing and I ran forward, flicking out my baton as I closed the distance.

I didn’t make it because, when I was almost there, Lesley threw Crew Cut at me. It was impello, of course, but that didn’t make 140 kilos of bad suit any less painful when it sails through the air and hits you in the chest – especially when you also have a duty of care and have to catch the bastard. So, while I was putting Crew Cut in the recovery position, Lesley went haring after Reynard.

Not far away I heard shouting and the sound of things breaking and, because I’m police, that’s the direction I ran in.

Guleed met me in the next room, running in with David Carey and a bunch of uniforms. He peeled off to deal with a member of the public who’d obviously been knocked down.

Guleed pointed to a ramp.

‘That way,’ she shouted.