The woman at the centre of a secret tape scandal which has cost Southland MP Todd Barclay his Parliamentary seat says the rookie politician should have resigned immediately.

Speaking for the first time since the explosive story broke this week, Glenys Dickson told Fairfax he should have gone earlier.

"I feel the honourable thing to do perhaps was to just resign immediately."

Barclay succumbed to mounting pressure this week and announced he would not contest his safe National seat at the general election following revelations about a secret recording of Dickson in the electorate office she worked.

READ MORE: English on Barclay: He's right to quit

His boss Prime Minister Bill English has been dragged into the scandal after confirming that Barclay had told him of the recording last year, despite the 27-year-old denying the allegations publicly for months.

Dickson, told Fairfax she felt "quite sad" for Barclay.

"He had a very bright future ahead of him and he just let himself down.

"There actually isn't any joy in me for going through this process."

He future with the National Party remained uncertain. She is currently a Gore District councillor.

"I just want to get on with my life and be a good councillor."

English today indicated that Barclay didn't know his recording of a staffer's conversations could be illegal until a police investigation was launched.

English revealed he told police in April last year that Barclay had confided he left a dictaphone running in his electorate office and had recordings of Dickson criticising Barclay.

Barclay, who had publicly denied taping her and refused to co-operate with the police, won't seek re-election as Clutha-Southland MP in the September election.

Speaking to media in Auckland, English said during the dispute his advice to Barclay had been that "that wasn't good behaviour".

When a police investigation started it raised issues about possible offences and "I don't think [it] had occurred to anybody that there may be some potential offence", English said.

English said once there was an investigation established the possibility of an offence became clearer.

"But earlier on, for those who weren't involved it was hard to know what exactly happened. There was no implication of behaviour that could be an offence.

"But nevertheless, whatever was part of the employment dispute, there was a police complaint [and] the information I had I made available to police."

It is illegal to intentionally intercept private communications you are not a party to.

After a complaint by Dickson police investigated for 10 months but found insufficient evidence for search warrants and to press charges. They are now assessing recently-publicised information.