“We are very clear that seeking to examine the mobile telephones of complainants and witnesses is not something that should be pursued as a matter of course in every case,” he said. “It is of vital importance that the personal information of those who report sexual offences is treated in a way that is consistent with both their right to privacy and with the interests of justice.” [J4MB emphasis. But the complainant’s “right to privacy” in this area is incompatible with the interests of justice – at least if “justice” includes justice for the alleged offender.]

A number of rape cases have collapsed in the past year after the defence got access at the 11th hour to evidence that had not previously been disclosed to them. Several defendants spent months on remand.

Mr Hill said that police and prosecutors were struggling to deal with disclosure in criminal trials because there was so much digital evidence.

Mr Hill, an experienced criminal barrister in both prosecution and defence work, said that “people increasingly live their lives — and so leave trails of evidence and information — on smartphones and social media. It is crucial that only reasonable lines of inquiry are pursued, to avoid unnecessary intrusion into a complainant’s personal life.”

In his Criminal Bar Association Kalisher lecture in London he said that this was a difficult line for investigators to walk.

“In 1997, when the Criminal Procedure and Investigations Act received Royal Assent, only 16 per cent of households in the UK owned a mobile telephone,” he said. “Google had yet to be launched, never mind Facebook or Twitter or social media messaging.

“Astonishingly, the technology in most of our pockets is more advanced than that which powered the first Nasa missions — and having seen the film First Man recently, that fact really struck home.” [J4MB emphasis. What an irrelevant point in the context of justice needing to be done.]

Mr Hill, who was the independent reviewer of terrorism legislation before starting his current role, outlined his priorities for his five-year term of office, insisting that he wanted to build public confidence and trust in the CPS. He said that he would be spending a morning prosecuting so that he could experience the workings of the magistrates’ courts for himself.