‘Stuart? Did you say Stuart?’

‘Yes, Stuart Clay, Les’s son.’

Fry stared at him. ‘Mr Massey, Stuart Clay died last year. He had pancreatic cancer.’

Massey looked completely uncomprehending. ‘That’s not possible. He was there on Wednesday.’

‘No.’

‘It was Stuart Clay, Les Clay’s son. I knew him – he was with us at the post that night. He killed Jimmy.’

Cooper shook his head. ‘DS Fry is right, Mr Massey. Stuart Clay died nearly a year ago. The man who visited you was his younger brother, Michael. Here’s a photo of him –’

‘That’s him: Stuart.’

‘No, it’s Michael. He was eight years younger than Stuart. Stuart would have been your age now.’

‘No.’

‘Michael had to deal with his brother’s affairs when he died,’ said Cooper. ‘We think that it was when he cleared out Stuart’s papers that he first came across references to the ROC and the post at Birchlow. Then he found other things – there was a cap badge, a photograph of the crew. And, above all, there were a lot of newspaper cuttings relating to the death of Jimmy Hind. That was why Michael came to have a look at the post while he was in Derbyshire. It was part of the process of putting his older brother’s memory to rest.’

But Massey still wasn’t convinced. It was obvious from the stubborn expression on his face, the distant, unconnected look in his pale, blue eyes.

For one last time, Cooper produced the photograph of the crew of the Birchlow observer post, Post 4 Romeo. He was confident that he was finally showing it to the right person.

‘Mr Massey, do you remember this photo?’

Massey screwed up his eyes, and held the photograph to the light.

‘That’s us, in the 1960s sometime. There’s me and Jimmy. The big bloke is Les Clay. And there’s Stuart Clay, Shirley Outram. I know all of them. They’re just as I remember them.’

In the photo, Jimmy Hind was wearing round, wire-rimmed glasses, like John Lennon’s. He was the only one in glasses, though Peter Massey had also been squinting a little as he looked at the camera.

‘Do you normally wear glasses, Mr Massey?’

‘Only when I need them.’

‘Are you short sighted, or long sighted?’

‘Short sighted, I suppose.’

‘If I left the room now, would you be able to describe my face to someone? Would you know me again if you saw me in forty years’ time?’

‘Why would I need to?’

Cooper lowered his head, no longer able to look Massey in the eye. He was thinking of the man who’d died in the underground bunker, starved of oxygen as the flood water crept higher around him.

‘Why?’ he said. ‘So that you don’t make a mistake about someone’s identity again.’

‘HE’S HOPELESS WITHOUT his glasses,’ said Cooper later, when he and Fry had concluded the interview. ‘He says he doesn’t need to wear them around the farm. He doesn’t miss anything that he wants to see. But there are some things he doesn’t want to see too clearly, anyway.’