‘I’m not rushing into anything,’ she replied. ‘Especially with my prime suspects in the McDiarmid murder currently lying on slabs down in Cal O’Shea’s laboratory.’ She wrinkled her nose in distaste, realising she could smell on her jacket an odour unsettlingly redolent of barbecue. ‘Suspects, I would add, that you made a point of trying to ward me away from earlier in my investigation.’

Abercorn ignored this and directed her attention to a mugshot among the piles of documents scattered about his desk. There was a black-and-white computer image clipped to it, showing a CCTV still from yesterday’s robbery.

‘This is the partial shot we’ve been circulating of the guy who robbed Coruscate,’ he told her. ‘He’s been identified as this man, name of Liam Whitaker. He’s a time-served thief and housebreaker, but the clincher is that he’s a known associate of Tommy Miller.’

‘We brought him in yet?’

‘He’s gone to ground.’

‘With a hundred and forty grand’s worth of jewellery, no wonder.’

‘Not jewellery,’ said Abercorn. ‘Watches.’

‘What’s the difference?’

‘These extremely upmarket watches are very popular among the higher echelons of the criminal fraternity.’

‘The blingest of the bling?’

‘No, you won’t find them actually wearing one. Way too valuable for that. They hold their value; in fact even appreciate sometimes. They’re an investment, for money-laundering purposes. Instead of having two hundred grand sitting around the house waiting for the Proceeds of Crime Act to come along and swoop it up, they have it sitting there in the shape of high-class watches worth ten and twenty grand a pop. Collector’s items. And when they want to liquidise some capital, they can sell them, legitimately.’

‘This isn’t telling me anything new. I had already worked out that Cairns’ tout must have planned to exploit the evacuation. This just gives us an idea of how much it was worth his while.’

‘He wasn’t only Cairns’ source,’ said Abercorn quietly, almost confessionally. ‘That’s the whole thing. He was our tout too, one of our CHISes. We were quietly keeping tabs on Callahan’s operation, but unbeknown to us, Miller was double-dealing the information. Guess it gives new meaning to the term Covert Human Intelligence Source.’

Catherine felt her eyes widen and tried not to indulge a sense of perverse satisfaction.

‘Which he knew he could get away with because he had sussed that you weren’t acting on it,’ she said. ‘Not directly, anyway.’

‘Well, that’s one way of looking at it, yes. We didn’t realise until today, and Cairns remains none the wiser.’

‘Is this why you got the charges against Gary Fleeting dropped?’

Abercorn’s mouth flapped silently for half a second, betraying his disquiet that she should know this. He tried to regroup but she could tell he was rattled.