A low cloud had drawn in over London and with it an early twilight. There’d been rain earlier and the smell of wet leaves mingled with the car exhaust. The traffic on Piccadilly was slow and it was easy enough to nip across, vault the safety railings and slip in through the gates.

Green Park had been laid down by Charles II, who nicked the land off a local farmer, laid out the paths and installed an ice house so that he’d never be short of a cool drink after a hard day of amateur theatre. It stayed on the fringes of the city where it served as a convenient open space for midnight liaisons and the occasional spot of highway robbery. It takes pride these days in being the dullest park in London and is noticeably short of shrubs, bushes, kiosks, statues or anything else a dashing constable about town might hide behind.

I should have welcomed the thick mist that seeped in between the upright tree trunks, hazing the street lights and beading my shoulders and the edge of my hood with droplets of water. But I didn’t.

Because I recognised that mist. I’d seen it roll up the Thames when Father and Mama held their Spring Court on the South Bank. And the course of the Tyburn ran through Green Park on its way to Buckingham Palace.

I keyed my Airwave.

‘Tyburn’s about,’ I said, my voice dulled by the moisture in the air.

‘So I see,’ said Nightingale. ‘Our fox is certainly living up to his reputation. I doubt Martin Chorley will risk entering the park while she’s on the warpath. Reynard’s safe while he stays in there.’

‘I can’t see them,’ I said.

‘Southeast of your position,’ said Nightingale. ‘Thirty yards and heading south.’

I stuck my hands in my pockets and slouched off down the path while trying to think delinquent thoughts.

They were a distinctive bunch, so I spotted them walking briskly across the grass towards the centre of the park. I picked up my pace, lifting my knees as if I was doing running practice. I figured I’d look kosher if I stayed on the path. I was crossing their path at a tangent and as I reached the closest approach I forced myself to keep my eyes forward – with luck, even if they looked, my face would be hidden by my hoodie.

Where could they be heading?

South was Constitution Hill Road, notable for not being much of a hill, and just beyond that the walled gardens of Buckingham Palace. Once they hit the road they could go east towards Victoria Memorial and the Mall or west up the hill to Hyde Park Corner.