‘OK. Now, at the risk of breaking my promises again, can you confirm that a call was made by Mr O’Driscoll at the same time as Mr Kash’s phone use? At 8.35pm?’

‘It was.’

‘And can you confirm that the cell site that picked up that call – Mr O’Driscoll’s call – was Mast Twenty-two?’

‘It was.’

‘So the same mast that picked up the phone use of both Mr O’Driscoll and Simon Kash ten minutes later?’

‘That’s correct.’

‘Thank you. Now, back in time a little more. In the hour before the 8.35 p.m. call, Simon Kash’s telephone was used a further seven times. Is that right?’

White checked his report.

‘It was.’

‘Thank you. Now, can you please tell me how many masts picked up one or more of those seven telephone uses?’

White checked his report. Then rechecked it more carefully. Michael watched him, amused. The expert was beginning to see the flaw in his analysis.

‘Two masts, Mr Devlin.’

‘Were either of those Mast Twenty-two, Mr White?’

‘No. They were not.’ White suddenly sounded much less sure of himself.

‘What about Mast Twenty?’

‘Yes. A number of the uses went to Mast Twenty.’

‘How many, Mr White?’

‘Five.’

‘Five of the seven. That’s very helpful. And the other two uses, Mr White?’

‘They were picked up by a different mast, Mr Devlin.’

White held up the map and pointed to another circled mast. One which seemed even further from the murder site.

‘Mast Thirteen.’

‘And Mast Thirteen is owned by?’

‘The EE network.’

‘And is that mast closer to or further from the site of the murders than Mast Twenty?’

‘It’s further away, Mr Devlin.’

There was a resignation in White’s voice. He knew what was coming. Michael could tell. White had seen his own mistake and there was nothing he could now do to rectify it.

‘How much further, Mr White?’

‘Perhaps half a mile.’

‘And how many other cell masts are there between Mast Twenty and Mast Thirteen?’

White counted. Twice. The expert was rechecking. Hoping his first count had been wrong. His face told Michael that it had not. Finally White answered.

‘Four, Mr Devlin.’

‘Four, Mr White? Four?’

‘Yes.’

Michael looked at the jury, feigning puzzlement. Some jurors seemed genuinely perplexed in return. But others were quicker; they had already reached the conclusion Michael had intended.

Michael pressed on for the remaining few jurors. Playing to the crowd.

‘So, Mr White. You told this jury today that Simon Kash’s phone signal being picked up by Mast Twenty-two proved that the telephone was at the site of the Galloways’ murders, very soon after their deaths.’

‘Yes.’

‘You also used the same data to conclude that Simon Kash’s phone was in that same location for a lengthy period before their deaths.’

‘I did.’

‘And you told this jury that this second conclusion was not undermined by the same phone being picked up by Mast Twenty just ten minutes before.’

‘That’s correct.’

‘You said that although Mast Twenty was half a mile from the scene of the murder and that there were five closer masts, it did not rule out the phone being at the scene.’