Bill English's text messages may be retrievable - expert

A computer forensic scientist says even if Prime Minister Bill English deleted the alleged 450 text messages sent to National Party staffer Glenys Dickson, they may be retrievable.

Security expert Daniel Ayers told Newshub mobile phone companies archive all text messages sent via their networks. The records are sometimes used by police in criminal prosecutions.

Winston Peters claims Mr English sent staffer Ms Dickson hundreds of text messages in the year before Ms Dickson left her job in Todd Barclay's Clutha-Southland electorate office. 

The existence of the text messages could put Mr English in a tricky spot - he's publically said he knows very little about the Barclay recording scandal, but Mr Peters says 22 of the messages were sent the day before Ms Dickson quit, and 25 the week after.

Mr English has not denied sending the alleged messages, but told media he has no record of them.

Asked if he had destroyed text messages that could be evidence in the police investigation of the alleged secret recording of Ms Dickson, Mr English replied, "There's no suggestion of the need for the texts or what's happened to them".

But Mr Ayers says those messages could be archived by Mr English's mobile phone provider, and Mr English could request a copy of them. He said all mobile companies archive all text messages.

"If the sender and recipient were subscribers of different telephone companies then the text messages in question may be archived by more than one carrier. 

"The length of time text messages are archived may vary by telephone company," he said.

Mr Ayers said if Mr English chose to, he could likely obtain copies of the text messages by requesting a copy of his personal information under the Privacy Act 1993.