He turns the file around so she can read it, taps his finger on a signature.

'The attempted robbery at Heathrow, six month ago. Mac didn' sign the file off, which means he was away. The Chief Super did it.'

Cogs are clicking in his brain, speeding up, starting to whirr.

'I don' think it's a coincidence but tha' isn't the point. He always goes away t'the same place in the West Country; a mate of his owns a hotel an' golf course. He takes the family there a few times a year.'

He sits up straight and opens another file. No luck with this one, or the next. Maybe it is just a coincidence.

'If he was involved, he'd 'ave wanted t'know how it went. He'd 'ave had to have someone phone him, or something, wouldn't he? If we can get the phone records an' check who he spoke to when he was away, we migh' find a trail. A name, somethin' to go on. People t'look into, at least. Someone calling who normally wouldn't when he's not at work.'

It's a long shot, he knows. A really long shot. But if Mac wasn't in London when these jobs went down, then surely another copper, or a criminal...or whoever he's working with...phoning him, would stick out like a sore thumb, in a way that wouldn't when he was back in his office.