Today is John Key’s last day in Parliament.

Key is 56 and has been in Parliament since 2002. By New Zealand standards he is both young for a former Prime Minister and has had a relatively short-lived term as an MP. Helen Clark was 59 and had been in Parliament for 28 years when she retired; Jim Bolger was 62 and had been in Parliament for 26 years when he retired.

There is thus an impression that Key was something of an opportunist who had chanced into a safe National seat in 2002 and then inside a dispirited and relatively lacklustre caucus, had quickly made it to the leadership four years after he arrived in Parliament.

But in a remarkably revealing interview in 2011 with Plunket Plunket, he revealed that he had always wanted to be a politician and Prime Minister.

Key came back to New Zealand in 2002 having made roughly $50 million after a career with Meryll Lynch in foreign exchange in Singapore, London and New York and challenged the sitting MP,  Brian Neeson for the same National seat of Helensville.

He won.

I always wanted to go into politics,” he told Plunket.

“ came back to run, it wasn’t an accidental thing, I didn’t just give up my banking career and say look I’m going to come back New Zealand I’ll see what happens next.

Plunket: “With the idea that you would lead the party and be the Prime Minister?”

Key: “Well I think every person who goes into politics, every MP wants to be Prime Minister.”

In fact, Key decided when he was ten that he would one day be Prime Minister and a millionaire.

His childhood was different, by New Zealand standards; his father an alcoholic British migrant who died while was young; his mother an Austrian  Jewish refugee from a wealthy family who died in the Holocaust and who ended up as a solo parent in Christchurch living in a state house.

I had a remarkable mother,” he said.

“I  had  the unconditional love that I think most children have for their parents, but in the case of my mother I also have great admiration, because here was a woman who was confronted twice in her life, once when she essentially was a Jewish refugee going into England, largely abandoned on her own when the war started in 1938, and secondly when Dad died, picking the children up and taking us to Christchurch.

“And so with my mother what I saw was that great belief in – she always would say, John, you get out of life what you put into it.

“And so I think I do have a positive attitude, and I do have a belief I can make a difference to my own life.”

In a particularly revealing section in the interview, Plunket, also the son of a solo mother, asked about Key’s father.

And Key responded with one his familiar claims not to remember.

“Mum taught me a lot of things, and one was look forward in life, don’t necessarily spend time looking back.

“She didn’t want me to sit around and feel sorry for myself, and there was nothing for me to feel sorry about, actually, there was a lot of love there. I mean yes I didn’t have two parents turning up to watch my rugby games, but actually, a lot of New Zealand children don’t have two parents turning up for a rugby game for a variety of reasons.

“The reality is that with Mum she said to me look you make the best of your life.”

The interview had been thoroughly researched, and it was suggested in Christchurch that Mrs Key was careful to indicate that she did not really belong in a state house.

Plunket “Did she tell you that you were better than Hollywood Ave? Did she tell you there was a better world out there for you?”

John Well she wanted me to be aspirational, she never you know stopped me wanting to do things with the one exception when I wanted to train horses, and she didn’t think that was a great idea for me to do that and leave school when I was 15.

“But outside of that yes she pushed me hard, and she had huge expectations of me, and she demanded standards.

“I remember once when I first started – I can’t remember whether I’d just started working, I got a cheque book, and I bounced a cheque, and she just hit the roof.

“She didn’t talk to me for two days, she basically grounded me even though I was at university, I mean there were rules, and you didn’t break those rules.

“She had high expectations of me, and it was the same things in terms of doing my homework all that sort of stuff.”

Key had an early political hero in Sir Robert Muldoon.

Plunket wondered whether that was connected to the absence of a father.

Plunket “Did you like Muldoon because he was a strong man and you didn’t have a Dad?”

KeyI don’t know. I’ve never gone and psychoanalysed it, I mean to be perfectly honest.”

“I just remember Muldoon as being a guy that was there at the forefront of our – I thought that whole political debate was interesting, and I thought it was interesting that in the end it’s a contest of ideals, it’s about what you believe and how you want to see the country shaped, and he stood up for what he believed in.”

There is a great deal more in this fascinating interview, the transcript of which can be downloaded below.

But the impression that it leaves is of a man moulded by a unique and very different childhood which imposed responsibility and ambition on him at an early age.

That he became what even some of his own colleagues call a “political freak” is now history.

Yet in a way, there has been less to Key than might meet the eye. Perhaps his political epitaph might come from this segment of the interview: “I don’t search for the centre of politics. I am in the centre of politics. I mean that’s where I am.