‘And you don’t think his involvement in a facial-recognition firm has any bearing on Kate’s accident or his subsequent relationship with her, a super recogniser?’ Silas knows he’s out of order now, adopting the wrong tone for speaking with his boss.

‘Not as far as I can see,’ Ward says. ‘Except perhaps in the context of Gilmour Martin trying to frame him. From what Rob’s told me today, it seems certain now that it was Gilmour at the scene of Kate’s accident that night.’

‘How many other forces are using Centaur?’ Silas asks.

‘Just us at the moment, but then Swindon has got more surveillance cameras than most. We’re in a position to make the best use of it. If the software lives up to its promises, Centaur’s going to drive crime off the streets of this town.’

Rob is proving a very good friend to Swindon.

‘The Irish are also looking at it,’ Ward continues. ‘So are the Germans. And I had a call from my opposite number in Nottingham last night. I’m not surprised. It’s a potential game changer. Promises closer interaction between humans and computers. No more embarrassingly high error rates.’ He pauses. ‘Are you liaising with the Met over Dr Varma? I don’t want any reports of non-cooperation.’

‘I’ve told them everything I know,’ Silas says. Almost everything.

Silas signs off and briefs Strover about Centaur. She’d already got the gist of it and is equally shocked.

‘I can’t believe he didn’t tell us,’ Silas says.

‘It’s the name that’s bothering me,’ Strover says, searching for something on her phone. ‘Know what a centaur looks like?’

Silas nods. He’d read about them when he visited the Pelion peninsula in Greece a few years back, when Conor still came with them on family holidays.

‘Half man, half horse,’ Strover continues, holding out her phone to show him a picture. ‘The combination of a computer’s artificial intelligence and the human brain is also known as the centaur model. After Garry Kasparov lost against IBM’s computer Deep Blue in 1997, he invented “advanced chess”, or “centaur chess”, in which grandmasters play against each other with computers.’

Silas made the mistake once of challenging Strover to a game. And he considers himself a half-decent player. He thinks about the documents on Dr Varma’s desk. The P3 brainwave, the articles on frozen addicts and locked-in syndrome. Centaur’s coming on-stream tonight – the day Dr Varma was killed, the day Kate was taken to France after having finally recovered her recognition skills.

His phone starts to ring. It’s Jake.

‘Where are you?’ Silas asks.

‘On a hillside in Brittany overlooking Rob’s house.’

The man is a like a dog with a bone. If he’d shown the same dedication to writing crime thrillers, he’d be a bestselling author by now.