The man blushed, beads of perspiration popping on his brow. He looked like he was out of his comfort zone in every way. Instead of addressing the clerk, he looked up at the judge in answer. ‘Affirmation, please, My Lord – I mean, Your Honour.’

Jupp smiled. The clerk handed him a card.

In a gruff voice, Ray Parker read the words on it. ‘I solemnly and sincerely declare and affirm that the evidence I shall give will be the truth, the whole truth and nothing but the truth.’

Jupp turned to the prosecutor. ‘Please proceed with your witness.’

‘Thank you, Your Honour.’ In a calm, measured voice, Cork asked, ‘Can you give your name and occupation to the jury, please?’

‘Raymond Parker. I work for the Sussex Police Digital Forensics Unit.’

Meg felt for the man. He was clearly a back-room boffin. The sort of person who was not comfortable talking to strangers – especially not under this kind of close scrutiny.

Cork responded. ‘So, you have worked there for three years, and prior to that you were employed for eleven years in British Telecom’s Digital Forensics Department, liaising with police forces around England, with your speciality being what is termed cell-site analysis, is that right?’

‘It is, yes.’

‘And in addition are you also an expert in identifying the location of mobile phones through their connectivity with local Wi-Fi installations?’

‘Yes, sir.’

‘You are in fact an expert witness in such matters?’

‘I am, sir.’

‘Can you please explain what work you do in the Sussex Police Digital Forensics Unit?’

Parker half turned towards the jury. Meg studied him hard. He looked a decent man, she decided, if a bit nervy. She would have been, too, in that box, in front of everyone. He stumbled over his first few words before he got into his stride.

‘Well, I’m sure many people in this court have heard that boast, by the phone companies, that even the most basic handset today contains more computing power than NASA had in 1969 when they put a man on the moon. But really, it’s no idle boast. Not only are phones getting more powerful by the day, they contain more and more data about their owners.’

Blinking hard, he stopped, pulled out a handkerchief and dabbed his forehead, before continuing. ‘This began as a cunning ploy by the phone companies to learn more about their customers, to find out their travel habits, their likes and dislikes, the purchases they made, to help target them for future sales. Technology is evolving rapidly. Today, people are carrying around in their handsets computers that will record an astonishing amount of data about who they contacted, what they said, where they were. A forensic download of that information can paint a detailed picture of their life.’ He was looking more confident now, Meg thought, comfortable expanding on his world. He managed a sly smile at the jurors.