Key Points:

Deputy Prime Minister Michael Cullen has apologised for a wisecrack he made about ripping off farmers on his parliamentary debut 26 years ago.

Dr Cullen was asked about the comment in his maiden speech in 1982 and whether he "resented wealth" on TV One's Agenda yesterday.

As the new MP for St Kilda, Dr Cullen said: "I'm proud of the fact that my secondary education was not paid for by the taxpayers of New Zealand but by the farmers of Canterbury and Hawkes Bay [he was given a scholarship to Christ's College]. I ripped them off for five years then, and I shall get stuck into them again in the next few years."

Dr Cullen told Agenda: "Oh, don't go back to that, that was one of the most embarrassing ... I want to apologise for that because what happened there was that somebody broke a longstanding convention, interjected on me one minute into my maiden speech, which was pretty unfair.

"I was wound up like a wire. This is my maiden speech in Parliament, you could have twanged me and I'd have played a whole concerto."

Hansard shows it was National MP Paul East - a lawyer - who interjected, bringing up Dr Cullen's education at the Christchurch private school.

Dr Cullen did not apologise for calling John Key a "rich prick" in Parliament. He explained to the programme that this was a reaction after his wife was brought into the debate and there was reference to Helen Clark being childless.

"I do think that was appalling behaviour and shows a real double standard that my comment back to him - and he was being a prick in saying that bluntly - was that it was then picked up."

He said he knew "lots of very wealthy people. I have no trouble with people being wealthy at all. What I have trouble with is people being poor."