Retiring Green MP Gareth Hughes says the pace of change in the current Government is not fast enough for his liking but that is not the reason he is quitting politics.

"It is not transformational on the scale of some of the big turning points in our country's history from the 1930s to the 1980s.

"There have been pockets of transformation but for me it has been a frustration that the pace of change hasn't been as fast as I'd like to see or in fact the Green Party would like to see."

He said he was retiring next election because 10 years was long enough and he and his wife wanted to travel the world with their two kids – aged 12 and nine - for a year.

"Talking to my wife, we feel it is the right time our life to spend some real solid quality time together and actually going travelling as a family would be a great way to do that and home-school the kids for a year."

He said he would possibly be making the same decision to leave had he been made a minister.

"I've been reflecting that my eldest is going to be 16 by the end of the next term and I have found it more difficult the older my kids have got because they are more aware of what's going on and dad's absence.

"My kids have grown up knowing nothing but a parliamentary life so I'm quite excited about spending more quality time with them.

"I always said that 10 years was about right and it feels right."

Hughes is one of only two men in the Green caucus of eight MPs and unsuccessfully contested the male co-leadership role in 2015 to fill Russel Norman's vacancy.

He rejected speculation that he may not have secured a winnable list position for next year's election.

"To be frank, it's going to be a guy's election for the Green Party, given the gender imbalance. I was confident that I would have been returned."

Green caucus from left: Jan Logie, Chloe Swarbrick, Gareth Hughes, James Shaw, Marama Davidson, Julie Anne Genter, Eugenie Sage and Golriz Gharahman.

Any prospect of promotion to a minister would have meant more time away from his children "and that would have broken my heart."

He has 10 areas of responsibility including energy and resources but has struggled for profile since the Greens entered Government for the first time in 2017.

In terms of lack of progress, he cited the capital gains tax – which did not have the numbers to pass in Parliament - and the ban on new offshore oil and gas exploration permits – but he also cited the ban as a high point.

"To push that in the confidence and supply negotiation [with Labour] but be unsuccessful but then to be able to achieve that afterwards was a real highlight."

The announcement of the ban in April 2018 was a shock because it had not been promised by Labour before the 2017 election, nor had it been in the confidence and supply agreement with the Greens - and officials had argued it would increase greenhouse gas emissions because of reliance on less efficiently produced imported fuel.

Hughes believed it was agreed in the end because of a confluence of factors – "good timing, groups such as Greenpeace were pushing incredibly hard at the same time and we made a very strong pitch to the Government that here was an opportunity to draw a line in the sand on what was our country's nuclear-free moment."

Hughes said a low point was losing colleagues along the way such as Russel Norman, whom he had been close to, and Catherine Delahunty.

He believed the party has done as well as it could have in Government.

"We've tried our best. We've got a tiny team that has worked their arses off for our policies and values.

"We've had some incredible wins; we've also had to compromise. We haven't always got our way. That was always going to be the nature of being in Government. I think we've as good a go as we possible could have."

Some of the wins were achieved behind the scenes in changes to Cabinet papers or proposals that cold not always be communicated.

If he had any advice for the Greens in a new term of Government it would be "that the Green Party's ambitions match the scale of the emergency."

"Climate change is getting worse, we need to fundamentally transform our society and we have to build a movement and inspire a whole new generation of people with a bold vision – to keep thinking big and transformational."

He has a laugh at the "thinking big" terminology, a world away from the Muldoon government's Think Big petro-chemical and energy-related projects that the Greens vigorously oppose.