Dragging her thoughts away from the bombs and the turf war, Sally settled down at the kitchen table with her laptop and notepad.

Her fingers flew over the keyboard as she opened up the files that had been pulled up for her, and one by one she started to eliminate possible suspects.

By lunchtime she was down to four people that had the position to be of use to Barrymore, and at least one had a gambling habit, which on the surface looked to be under control, but warranted deeper investigation.

Pushing aside her work she made another cup of coffee, and helped herself to the makings of a cheese sandwich then switched on the portable TV on the work unit and watched the one o'clock news.

She watched as Lestrade was interviewed by the BBC news crew, followed by identical statements from Gregson and Dimmock at the other scenes, then finishing her lunch she flipped the television off and pulled her laptop back towards her.

As it powered up again, she realised that she had seen something. Something so commonplace that it was easily overlooked in internal investigations.

Working quickly, she scanned through screen after screen, looking for the last piece of the puzzle, then, with a sigh she sat back in her chair and whistled through her teeth.

"Bingo!"