‘Yes.’

‘And therefore consistent with that telephone being in the same place as the telephone of Mr O’Driscoll? Despite the two phones registering on different masts?’

‘Yes.’

‘On the basis of a mast’s limited signal capacity.’

‘Yes.’

‘OK. In that case, just one more thing, Mr White. You explained earlier how a mast will prioritise its own use.’

‘I did.’

‘So the O2 masts we have looked at would prioritise O2 users, and the EE masts would prioritise EE users.’

‘Yes.’

‘There is another aspect to this though, isn’t there? The aspect that comes into play after capacity has been reached. Because the prioritisation continues even then, doesn’t it?’

‘Yes, that’s correct.’

‘Which means that if a mast is at capacity and then a user from its own network comes calling, the mast will eject a user from a different network to make room. That’s right, isn’t it?’

‘It is, yes.’ White was relieved to be back on firm ground. ‘That’s why mobile calls are sometimes mysteriously cut off. Because, let’s say, an EE phone is using up the last space on an O2 mast, then an O2 user tries to “log on”. In those circumstances the O2 mast will eject the EE signal to accommodate the O2 signal.’

‘That’s what I thought. And I’m glad you used that particular example, Mr White. Because, as you’ve told us, Mast Twenty-two belongs to the O2 network, doesn’t it?’

‘That’s right.’

‘And it also happens to be the mast closest to the murder site and therefore the mast most likely to be used by a phone user at that location.’

‘If it has available capacity—’ White began.

‘Yes, we appreciate all of that.’ Michael denied White the chance to digress. ‘And it’s right, isn’t it, that Mr O’Driscoll’s telephone was picked up by that same O2 mast on each of its uses in the hour prior to the last use at 8.45 p.m., correct?’

‘Yes.’

‘Which is why you conclude that Mr O’Driscoll’s phone was at the murder scene during that time.’

‘Yes.’

‘Exactly.’ Michael picked up the telephone bundle once again. ‘Mr White, can we turn to page four of the bundle?’

White did as requested. The judge, jury and all other barristers did the same.

‘If we look halfway down the log of phone uses, we see that two of Simon Kash’s eight uses are almost simultaneous to two of Darren O’Driscoll’s uses. Can you see that?’

White studied the data.

‘Yes.’

‘Mr O’Driscoll made a call at 8.11 p.m. For three minutes. Registered at Mast Twenty-two.’

‘Correct.’

‘And at 8.12 p.m. Simon Kash made a one-minute call, registered at Mast Twenty.’

‘I see that, yes.’

‘Then we look further down. To 8.31 p.m. Mr O’Driscoll made another three-minute call. Mast Twenty-two again. A minute later Simon Kash made what seems to be an aborted call. Registered at Mast Thirteen. A mast that is a full mile away, as we know.’

‘Yes.’

‘And which is an EE mast.’

‘Yes.’

‘Are you aware of the phone networks that provide service to Mr O’Driscoll and to Simon Kash, Mr White?’