‘I think you’ll find that is a matter for us to decide.’ Barrett showed little tolerance.

‘Well, I mean, Grant and Shirley, they seem happy enough to me. I’ve known men with wandering eyes in my life. Not my Alfred, I mean,’ she said, patting her husband’s arm. ‘But usually they grow out of it. It sounded to me like Grant was immature. But people change.’ Neither detective could be sure whether she had said this for their benefit or her own. ‘I can’t stand the idea of Grant and Shirley having their marriage wrecked for something that is in the past. It just wouldn’t be right. What’s done is done. Water under the bridge and all that.’

Palmer chewed his lip, wondering if she meant it.

‘Do you think Grant Grubb was aware you knew about the affair? Did anyone else know about the affair?’

‘Well, Mike knew.’ Marion felt like she’d accidently put Mike right in the firing line, and stopped abruptly.

‘He knew the identity of the man his wife had been sleeping with?’ Barrett pressed.

‘You’d have to ask him to be sure.’ Marion had said enough and saw no reason to speculate, or frame someone she considered to have had nothing to do with Toni’s death. ‘Mike’s a happily married man now, as far as I know.’

Realising they had got the information they had wanted from Marion, Barrett brought an end to the interview.

‘Well, Mr and Mrs Bolton,’ he said, standing to signal that the interrogation was over, ‘I’d like to thank you for your time today. If we need anything further, an officer will be in touch.’

Not used to being dismissed like small children, the Boltons stood and, guided by Palmer, shuffled out of the interview room.

Elly Hale was relieved to see Barrett and Palmer when they reappeared in the incident room.

‘Sir, we’ve had information from forensics. They have confirmed that the victim did have a fractured skull, as a result of blunt force trauma, when she went into the water. There was also water in her lungs, so they know she was still alive when she went into the river. They are doing further tests and will keep us up to date as soon as they know any more. The pathologist says that from the appearance of the injury, she was hit with something. Hard. Repeatedly.’

‘Just like Toni Jones.’ Palmer mused.

‘Yes, but according to the report, the injuries did not break the skin and there was no blood on the victim or around the contusions.’ Elly looked pale as she read the clinical notes.

‘What about the marks on the neck?’ Barrett asked.

‘Well, there is bruising, but it is apparently light. No official post-mortem can take place until the Home Office pathologist has arrived though.’