John Key gives his final speech to Parliament today after spending 15 years in the place, eight of them as Prime Minister.

Mr Key was one of our most popular leaders ever, keeping his party nudging close to 50 percent during his time in office.

Mr Key's kept a low profile since he suddenly stepped down from the top job in December and said he's heard all the rumours that he'd been having affairs and there was trouble with his son Max.

None of it was true, he said he wanted to pick the right time to ensure National had a good chance of a fourth term and he reckons he picked it right.

"People were surprised when I left investment banking when I was 40, I never saw myself in [politics] when I was 71, Winston Peters might like it, but it wouldn't be for me when I'm 70."

As for his popularity, Mr Key believes it was his ability to fool around and not take himself too seriously.

Mr Key said he's the sort of personality that would play along with pranks and not to worry too much about them.

He said he'll leave with no regrets.

"I think I'll always have really fond memories of this place. You always feel a degree of nostalgia when you go back which inevitably I will do from time to time for events, but I don't think I've made the wrong decision. I'm not about to do the famous David Lange 'I've changed my mind'."

Meanwhile, Bill English has virtually confirmed a knighthood's on the way for Key following his departure.

It could be as soon as June with the Queen's Birthday honours.

Mr Key said it's not something he spends much time thinking about though.

He said he doesn't need a knighthood to mark his time in politics and said if it happens, it happens.