John Key's legacy: A confident New Zealand

Former Prime Minister John Key says he's in "an incredibly good space" as he approaches his final day in Parliament on Wednesday.

Mr Key sees his legacy as a more confident New Zealand.

"You've got to be careful about claiming credit for everything, but I think there's no question we're a more confident nation now, and New Zealanders really do have quite a spring in their step.

"I think they do feel as though as a country we're punching above our weight on the world stage," he said in an interview with Newshub political editor Patrick Gower.

"That suits my personality, by definition I'm an optimistic person, I'm a bit of a pragmatist, I want to get things done. You know, I'm more interested in results and how you actually got there."

Mr Key regrets that his vision for a new New Zealand flag was never realised, and it never gained the support of Labour and the Greens.

"I liked this concept of New Zealanders having a flag that was quintessentially Kiwi, and not some other country's flag. In the end it didn't happen."

He doesn't think the flag referendum result was due to a failure of design.

"There were over 10,000 designs, every designer in New Zealand and indeed around the world had an opportunity to submit."

Mr Key is also disappointed that the Trans-Pacific Partnership Agreement fell through.

Donald Trump stopped the TPPA dead in its tracks as soon as he became US President, a blow to what could have been a major part of Mr Key's legacy.

"From New Zealand's point of view I always back New Zealand companies to do well, and I think if you give them a level playing field they'll succeed. I always thought those opponents to the TPP were massively exaggerating the negatives, and the benefits well and truly, as history has proven in other free trade agreements, outstrip those."