He was a middle-aged white man in a good-quality but otherwise nondescript bespoke suit. He held what looked like a semi-automatic pistol in his right hand and a Kobbé’s opera guide in his left. He wore a white carnation in his buttonhole.

Nightingale fell down quickly. He just slipped to his knees and flopped forward onto his face. He let go of his cane and it rattled on the paving stones.

The man in the good suit looked at me, his eyes pale and colourless in the sodium light of the streetlamps, and winked. ‘That’s the way to do it,’ he said.

You can run away from a man with a handgun, especially in poor lighting conditions, provided you remember to zigzag and can open the range fast enough. I’m not saying that option wasn’t tempting, but if I ran then there was nothing to stop the gunman from stepping forward and shooting Nightingale in the head. I was trained to placate the gunman while edging backwards; talking establishes a rapport and keeps the suspect’s focus on the officer so that the civilians can get clear. Ever see The Blue Lamp with Jack Warner and Dirk Bogarde? During our training at Hendon, they made us watch the scene where PC Dixon, Warner’s character, is shot dead. The film was written by an ex-copper who knew what he was talking about. Dixon dies because he’s a dinosaur who stupidly advances on an armed suspect. Our instructors were clear: don’t crowd, don’t threaten, keep talking and backing away, a suspect has to be particularly stupid, political or, in one memorable case, protected by diplomatic immunity to think that killing a police officer will in any way make their situation any better. At the very least you’re buying enough time for an armed response team to arrive and blow the silly bugger’s head off.

I didn’t think that backing off was an option. This was one of Henry Pyke’s sequestrated puppets, and wouldn’t hesitate to shoot me or Nightingale no matter how calmly I was talking.

To be honest, I didn’t think at all. My brain went: Nightingale down – gun – spell!

‘Impello!’ I said as calmly as I could, and levitated the man’s left foot one metre in the air. He screamed as his body was catapulted upwards and to the right. I must have lost concentration because I heard the distinct crack of a bone breaking in his ankle. The gun fell out of his hand and his arms flailed as he tumbled to the ground. I stepped forward and kicked the gun down the street, then kicked him once in the head, hard, just to make sure.