‘Not very likely at all, Mr Epstein.’ White had held up the larger map to assist. He continued. ‘As you can see, there are many, many masts in this five-mile area. Each has three cell zones, as we’ve seen. Each cell zone has a significant capacity, and the phone use on each mast is prioritised. The top priority are the calls that come from telephones on the mast’s own network. You see, each mast is owned by a particular network. For example, our Mast One could be owned by EE, while our Mast Two could be owned by Virgin. Each mast will give preference to calls or texts that come from its own network. But assuming it has capacity left, then it’s first come, first served; it will take calls from phones of other networks. So most of the time any mast will take a call from any network. It is therefore very, very unlikely that all masts within a small area would all be at capacity. The idea that a phone wouldn’t be able to use one of the masts close by, that instead it would need to connect to one that is, say, a mile away from the phone’s physical location, is extremely unlikely indeed.’

With the jury up to speed on the theory, White moved on to the evidence in the case.

Using cell-site data relating to O’Driscoll and Kash’s telephones, he explained how their movements could be tracked, placing both phones at the scene of the Galloway murders. He then used the same data to show the jury the route he believed at least Darren O’Driscoll’s telephone had taken. A route, he said, which mirrored the Galloways’ own journey and so suggested that the brothers had been followed. And then, he said, the same data showed both telephones leaving the area shortly after the brothers’ time of death.

By the end of White’s evidence to Epstein, the jury had a clear picture of all the cell-site evidence, a picture that wholeheartedly supported the prosecution’s case. And a picture that Michael was sure was wrong.

Once Epstein had finished and taken his seat, Cole had cross-examined White for his own client, O’Driscoll. He had attempted to undermine White’s conclusion that O’Driscoll’s telephone had been at the scene of the Galloways’ murders. Although Cole’s questions had been asked skilfully, Michael knew he was coming at it from the wrong angle; White’s evidence had not been hurt.

But Michael was not concerned. As he rose to his feet, he knew he could do better.

‘Mr White, I’m going to ask you some questions on behalf of the defendant Simon Kash.’

‘I understand, Mr Devlin.’

White had encountered Michael before.

‘Then you’ll also understand, Mr White, that I have nothing to ask you about Mr O’Driscoll’s telephone.’

‘I think I’ve been asked all there is on that one.’

White smiled as he delivered his answer. The jury did the same. They seemed to agree.

‘And it is possible for me to leave Mr O’Driscoll’s telephone alone, isn’t it?’ Michael continued. ‘Because you don’t actually suggest that Mr O’Driscoll’s telephone and Mr Kash’s telephone travelled together, do you? Or that they even took the same route?’