‘Presumably that is why he got rid of the bodies into the river,’ Gillard said. ‘The freezer he had been relying on for decades finally packed up, soon after he dumped Beatrice into it.’

‘That’s right,’ Otara responded. ‘We think there was a power surge during the thunderstorm on Sunday. Halliday was able to monitor the electricity from an app, and must have realised immediately, and driven over to try to rectify the situation.’

‘But what about the other bits of chiller kit there?’ Gillard asked. ‘There was enough to freeze the car.’

‘My guess is that he saw a problem and an opportunity,’ Otara said. ‘Once he realised the extent of the flooding, he saw that it was a chance to dispose of a couple of the bodies in circumstances that might not draw attention to him. Stowing them inside the Allegro put someone else in the frame. If the bodies had been lost in the water for, say, another three or four days, they would have been much harder to identify, particularly Jane Morris.’

Rainy Macintosh put up her hand. ‘We know from credit card activity that Halliday had ordered another big industrial freezer, but there was a week-long delay in delivery,’ she said. ‘He would have been left with three decomposing bodies in the meantime. He only got the big chillers delivered a couple of days after, and they would never have been a long-term solution.’

‘That’s all beginning to make sense,’ Gillard said. ‘But what strikes me now is that it was only because he was trying to get revenge on me that he kept Sam alive. Otherwise she’d have been killed and then frozen with the others.’

A hush descended on the incident room, as all eyes turned to Gillard.

Otara addressed him directly. ‘You can take great solace in having cracked the riddle so quickly. Even another minute in that inspection pit and she would have drowned.’

After the meeting finished Gillard and DI John Perry remained in the incident room while DCs Rainy Macintosh and Rob Townsend showed them Kyle Halliday’s silver briefcase, found yesterday at the barn. ‘What we’ve got here is his complete box of tricks,’ Rainy said. She opened the lid to reveal a foam insert, in which a small laptop and six mobile phones were embedded. There were spaces for half a dozen more. ‘Each mobile phone is used only for one woman. The social media, the photographs, text messages and so on only correspond to a particular relationship.’

Rob Townsend meanwhile had broken into Halliday’s laptop, and opened up a large spreadsheet with colour-coded columns, each headed with a woman’s name, and a series of dates marked on the rows. ‘This is the master spreadsheet, which details exactly who he’s seeing, when, and which particular set of lies he has told them. He has written and presumably memorised everything he learned about their families and life history, so he doesn’t get mixed up.’

‘Incredible,’ Gillard said.

‘Aye, our Mr Halliday made a note of the wedding anniversary of Ellen Bramley’s parents, even though he only dated her for a few months,’ Rainy said. ‘Whereas my ex, bless his cotton socks, was married to me for a decade and couldn’t even remember my birthday.’