"I suspect they'll stick with John," he said. "I'll be more than happy with that."
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Key was made a Knight Grand Companion of the New Zealand Order of Merit, a level one honour which most former New Zealand leaders have been offered.
He said Prime Minister Bill English initially texted him to tell him what the honours and appointments committee had in mind, telling him he had better take it.
The later citation prepared by officials includes mentions of Key leading New Zealand's response to the global financial crisis, a series of major disasters, Treaty of Waitangi settlements, closer relations with the United States, withdrawal of troops from Afghanistan, securing a seat on the UN Security Council - and the national cycleway project, which particularly amused Key.
"I said to Bill I've to be the only person in the world that's got a knighthood for a cycleway."
But he said the honour reflected a huge team effort including "millions of New Zealanders who through their voting patterns allowed us to be the Government.
"There are so many people what have part of the story and in my case it was an incredibly capable and talented cabinet and caucus.
"I'm immensely proud of the honour but also very cognisant of the fact that it is something you share through the deeds and actions of other people."
That included his family. Key and his wife, Lady Bronagh, told their children, Max and Stephie, about the honour last weekend and Key says they were thrilled for him.
"It doesn't change anything for them but I think it is one of those things where for future generations of our family, it will always be a nice thing that was there."
He said Max was living at home at present and studying for exams. He had two months to go before finishing his degree.
I suspect they'll stick with John. I'll be more than happy with that.
Stephie had been in Wellington working on costumes for Sir Peter Jackson's new movie, Mortal Engines, for the past eight months and was preparing to move to Los Angeles to work.
"She's been loving it. She has been a changed girl. She's up at 4.30 in the morning and going into work, a whole new world."
Key's whole family was invited by the Queen to spend a weekend at Balmoral Castle in 2013 and he is a strong supporter of New Zealand's constitutional monarchy.
But he said his reintroduction of titular honours (damehoods and knighthoods) in 2009 had nothing to do with the monarchy.
"And it wasn't because I wanted to get one, despite the rumours," he said.
It was because the abolition of them in 2000 by Helen Clark had led to a level of confusion with the public and they had not known the various levels and what they meant.
Commenting on being made a knight instead of a member of the Order of New Zealand, he said: "It's horses for courses. They are both level one honours. They are both in my mind the same."
"They offered me the knighthood because they knew I had brought them back and that would seem a natural fit.
"When I was Prime Minister and I chaired the committee, I offered Helen Clark the Order of New Zealand because having abolished damehoods, it would be insulting of me to offer her that."
I am well and truly gone.
He said would not be asking for his investiture to take place at Buckingham Palace.
He wanted it to take place in New Zealand.
Key is still adjusting to life outside of politics since resigning suddenly in December. He has been doing a lot of travel including as representative for golf-loving Japanese billionaire and philanthropist Dr Haruhisa Handa.
He and Lady Bronagh will be taking a few months holiday in Italy and Croatia soon.
He has been sorting out a few more directorships and international jobs for next year which he cant yet reveal.
He has also been doing some international speaking, including in Brisbane and Perth for PWC on the Australian Budget - "I had a bit of a clue because I'd spoken to Malcolm Turnbull on the weekend."
He enjoyed watching the New Zealand Budget from his Parnell home on May 25.
"I sat down with some popcorn and a cup of tea and watched it."
He texted Finance Minister Steven Joyce and English after it to tell them it was a great Budget "and I think it is an election-winning Budget."
He said he had offered Bill English a couple of one-liners to use in his Budget speech, but he hadn't used either.
"I'm well and truly gone."