By Craig McCulloch of RNZ

New Zealand First leader Winston Peters has accused some of those defending his High Court action of "covering their butts" and others of suffering a "memory lapse".

Peters argues his privacy was breached in 2017 when officials notified then-National ministers that the MP had been overpaid his superannuation. Upon being notified of the error, Peters repaid nearly $18,000.

He is seeking $1.8 million in damages.

Part of the second day of Peters' privacy case at the High Court at Auckland focused on the 2010 meeting where he applied for his pension and the mistake which led to the overpayment.

A question on the application form was left incomplete, resulting in Peters being recorded as single when he was in fact in a relationship with Jan Trotman.

The Deputy PM said Trotman was with him when he filled out the form at a Ministry of Social Development branch office and that he introduced her as his partner.

But Crown lawyer Victoria Casey QC put to Peters that three frontline staff said the MP was alone during that meeting, including one who was "very sure" Trotman was not there.

Peters told the court that was a "desperate" claim.

"Some people in this defence are covering their butts and it's clear as daylight."

Peters said it wasn't surprising that some staff would not remember Trotman as she had attended thousands of meetings and was adept at going unnoticed. "A receptionist, nine years later, remembering somebody who was behind me? How would that person remember Jan?"

Casey also put to Peters that his partner's presence was "[beside] the point" as it was ultimately his application which was being filled out.

Peters shot back that he would find it "extraordinary" to ignore that as a key fact.

"The fact that everyone had a memory lapse as to her presence, I find that extraordinary."

Trotman in evidence backed up Peters' story, saying she was "absolutely sure" she went to the MSD office and stood to one side while he approached the receptionist.

She said she sat in on the interview with Peters and a case manager while the application was filled out.