As the hills of the Downs faded into the distance and the two cars started to pass through ever-shrinking villages and hamlets, Laing let his mind range across all the possible excuses it had come up with for what was happening since he’d left Highgate. Was there a simple, innocent explanation for why Knox had driven a stranger from the director general of MI5’s home to the Garden of England? Or were the Service’s most senior officers up to something they didn’t want anyone to know about, and using the summit as a distraction? Laing didn’t like that possibility, mainly because it would mean they were using him to help create their cover while also keeping him in the dark about their plans.

He was momentarily distracted from his spiral of thoughts by a flock of birds bursting from the hedge that ran along the side of the road, flapping up into the wide blue sky in every direction.

A second later, the source of their sudden take-off appeared: a plane flying so low it looked like it was going to crash into the row of bushes.

The aircraft crossed the road just fifty feet off the ground and only a hundred in front of Laing’s car, yet even that close it looked tiny to him, like someone had strapped a couple of wings across the top of a Mini. It was a Piper PA-18 Super Cub, with a cabin barely large enough to fit its pilot, and a wingspan of only thirty-five feet.

Laing watched it get lower and lower beyond the hedge, and guessed there must be an airstrip on the other side.

He looked back at the road just in time to see Knox’s Jaguar make another turn outside a town of small pastel buildings with brown pitched roofs and a single tall, square church tower. And then he was distracted again, by the Doppler roar of a motorbike overtaking him. It was travelling too fast for him to make out any details, and it was only when it slowed momentarily to take the same turn Knox had that Laing saw there were two people on it. If they were a couple out for a countryside ride they seemed to be in a hell of a rush to get it over with.

Laing dropped down through his gears as he approached the junction so Knox wouldn’t spot the Consul if the motorbike made him glance in his rear-view mirror. Then he turned into the next stretch of country road.

The hedge that had blocked his view of the little plane’s final descent continued along one side of his path, but on the other the flat fields that had replaced the Downs now gave way in quick succession to a series of wide marshes and then a vast shingle beach.

Laing had arrived at Dungeness.