"I kind of always had a plan for what I would do if I was diagnosed with breast cancer," Harre says.
"It was a really easy decision for me to make and it was absolutely focused on maximum reduction of risk."
Harre has been out of Parliament since 2002 when, after just one term in coalition Government with Labour, the Alliance split in spectacular fashion from its founder leader Jim Anderton.
She counts paid parental leave, Kiwibank and improving conditions for collective bargaining as major features of the Alliance's legacy.
Since then she has worked for the Nurses Organisation, the National Distribution Union, the Auckland Transition Agency and the International Labour Organisation (ILO).
A few weeks ago, she started work for the Green Party in Auckland as issues director.
Thanks to reconstruction surgery, she also has a set of plump new breasts - slightly larger than before, though minus nipples.
Harre was sitting in a car with husband Barry Gribben at Treble Cone skifield near Wanaka when she got the confirmation she had cancer.
She had asked that the results be held until the end of a scheduled family skiing holiday, a trip that was all the more precious because she had been working overseas at the time, in Fiji, and squeezing trips back home every six weeks or so.
The time between the confirmation of the cancer and the operation was 13 days.
She was given the all-clear earlier this year and says she has a great prognosis.
Breast reconstruction was done at the same time as the double mastectomy.
Sometimes surgeons use a patient's own body tissue but she didn't have enough to spare - "one of the downsides of staying trim and fit" (she ran a sub-four-hour marathon at Rotorua a few weeks ago).
She was fitted with what are called "expander implants" made of silicone and "ports" on either side of the breasts through which saline is injected over several months, as the natural muscle covering the implants expands. Then the ports are removed.
"There were a few moments of mirth, such as when I was being asked what size implants I wanted and I said I would like the same size as before and he [the surgeon] said, 'We don't make them that small.'
"There could certainly be a market in smaller breast implants, so my breasts are slightly bigger than they were but I opted for the least change possible."
Harre says she is getting used to them. They don't feel completely natural but she is very happy with them.
But can she feel them or would she feel it if she pricked herself with a pin?
"If I was to prick myself with a pin there might be a silicone disaster. I don't think I'll experiment with that."
She says she would have had every confidence in the public system but had the operation at Brightside Hospital, taking advantage of the private health insurance that was part of her employment package with the ILO in Suva, a job she started in 2010.
For some people such operations can be traumatic and change their attitude to life.
"The way I dealt with it was to get through each point and not let it change my life."
She concedes it has changed some things. All other things being equal, were it not for the cancer she would probably still be working in Suva, a place she calls her first home.
She spent what she calls "an idyllic childhood" living there while her father worked as an anthropologist at the University of the South Pacific.
Had she stayed she could have begun a career with the ILO with further international postings but she chose to return home to Auckland to be closer to Barry and their two sons.
The experience also made her reassess what really mattered to her. As a result she says she is less tolerant.
"To put it more positively, more focused on making the kind of places you spend time in positive."
She was going in to a role with the Greens where she would be leading a team working on some difficult issues.
"For me, one of the most important things I can do is to create a work environment where people are able to be effective, where there is a very genuine commitment to effective teamwork and a workplace culture that is healthy and happy, and that people feel great about coming to work and the contribution they can make at work.
"That sort of thing is of primary importance to me now.
"I think we put up with a lot of compromises in our work or home environment in all sorts of ways and I feel a lot less compromising about things - being healthy, happy, functional as a result of this."
Harre will be leading the Greens' out-of-Parliament support staff, who she says have been consolidated into a single team to help the party's MPs reach out into communities around New Zealand.
The team are currently working with other organisations in a campaign to get a citizens-initiated referendum on asset sales, on dirty rivers, the use of water resources, mining, fracking, deep-seas drilling and Auckland transport.
Harre will be avoiding sitting in traffic for up to an hour a day when she and the family shift from their home in Te Atatu to a new home in Mt Eden, closer to work.
She hasn't yet joined the party but Green politics are not new to Harre.
Her former NewLabour Party and the Greens were both constituent parties of the Alliance and she will be meeting up with some of the Greens from that time at the party's conference in Wellington this weekend.
Would she stand for parliament again herself?
"I haven't even considered it," she says. "And I feel really happy to be part of the growing influence and relevance of the Green Party, both as a force in Opposition and as a major player in government."
She thinks Labour and the Greens and others are headed for the Treasury benches next election.
But the most important thing was what a new government would do to address issues such as inequality, public services and the reduction of New Zealand's overall indebtedness.
"It's certainly just not enough to regain government."
Laila Harre on ...
The Alliance's split with Jim Anderton
I still have a reserve of grief over the demise of the Alliance and all that hope that I had invested in that whole project, but I think I'm through the angry stage.
I didn't see the Alliance split coming and I wish I had. It really did come to me as a bolt from the blue.
It was only after the event that I began to work out what must have happened.
I was genuinely oblivious to the depth of the division that had developed between Jim and others.
It was possibly unavoidable, not so much because of any of the issues themselves but because from Jim's point of view, the Alliance project had finished and it wasn't where he was at.
NZ's sanctions against Fiji's military regime
I went [to Suva] with a pre-conceived view of NZ's position and that didn't change over the period I was there. I don't think there was any evidence that New Zealand and Australia's position had made things better or increased the chance of restoring democracy.
There is some evidence it has made things worse. That approach increased the sense of embattlement around the Government. It almost certainly led to tighter controls on the media and other forms of civil control designed to secure the Government against internal risk because they perceived themselves to be under siege from outside.
There is a developing broad willingness to now go with the process the Government has set up [towards elections in 2014]. I think the main view now is that working with the process is likely to make it inevitable whereas working against it might put it at risk. That is probably the predominant view of people whether or not they have been supporters of the Government.
