KEY POINTS:
Katherine Rich is trying to explain exactly why an MP would sit in Opposition for nine years and leave just when the scent of Government is tantalisingly close.
It has been an emotional day and at times she gets a bit squeaky and looks away.
She has told all her caucus colleagues only that morning that she's retiring.
One of them - Simon Power, who entered Parliament on the same date in 1999 - is quietly sitting beside her now for moral support.
Dubbed the Young Guns, their names were often jokingly linked by opponents as synonymous with National Party values - Rich and Power.
Now Ms Rich, 40, is leaving to spend more time with her two children, aged 7 and 5. Some thought she was mad, National's shining star quitting on the verge of the election she is convinced her party will win.
In fact, it was the prospect of government that put her off.
She realised if National won the next election she would likely be the Education Minister and spend so much time looking after the children of New Zealand that her own would miss out.
"There are those who say this is unbelievable. But I've thought very deeply about this and I know what has to be done.
"You are put in here to serve the people of New Zealand. Now I've got two other little people to serve.
"The Ministry of Education has over 2500 schools and they all want to see you. There are all the sector groups and they want to see you, as they should.
"I know I would do a good job, but I felt I couldn't do that without severely impacting on [my children's] lives."
Ms Rich has figured out she has now spent a quarter of her life in Parliament and "I think I've been a good shin-kicker over the years".
But there is no best of both worlds for Katherine Rich.
She says it isn't in her character to consider taking a lesser role in government to give her more time at home than a major portfolio will allow.
"I could have, but I've always aspired to be the best I can. To come back in a junior role might have been tougher for me."
She's proud of standing her ground, even when it went against the caucus line. There was the anti-smacking bill, which she was the only National MP to publicly support until Mr Key signed a compromise agreement on the bill.
There was also the run-in with Don Brash over his hard line on welfare benefits. She lost her welfare portfolio because she refused to back him.
She now says she was "pushed beyond my ability to compromise".
"In some ways that was the making of me. I came into politics to have a view, and to fight for what you believe in."
She is quite affronted at any suggestion that the rough and tumble of politics can be hard to take and says she always cringed when others leaving described Parliament as a harsh environment.
"Well, this is politics, it's not the local Plunket branch."
Asked for her plans, she says she has offered to be a select committee "sub" for her colleagues to give them time to get out in their electorates. She swears she likes select committee work.
Longer-term plans have not yet been made, but Dunedin needn't expect a Mayor Katherine any time soon. The suggestion of local body politics provokes a snort and "get off the grass!"
"If I show an interest in local body politics, I've told my family to lock me in the cupboard."
