"Just being in the changing room, obviously having won a world cup the atmosphere is going to be one of elation but it does run deeper than that."
The team had spent a lot of thinking through every eventuality.
They told me they tried to think through every scenario - what happened if they lost a player like they did, what happened if they lost a back like they did. They really didn't leave anything to chance."
Willie Apiata VC was brought in to help with their mental preparation for the past two weeks and was at hand around the prize-giving podium and in the dressing room afterwards.
Mr Key said Dan Carter's drop kick when Australia were only four points behind New Zealand had to be the most important drop goal he had ever kicked in his life.
Asked what it was like in the dressing room today, Mr Key said it was "unbelievably good" and there was probably a greater sense of elation after today's win than in 2011
" I think in 2011 there was mental exhaustion of having won after such a long period of time when it was so close."
Mr Key agreed that departure of a large group of senior players after World Cup was not the sort of succession planning a political party would want, "what we know about New Zealand rugby is that new talent will blossom and grow and turn into legends of the game as well."
"The hallmark of this team and actually of New Zealand rugby is its bench strength. "
Mr Key said he did not have a formal bet with Australian Prime Minister Malcolm Turnbull but had texted him last week to suggest they wear the other's tie for a day in Parliament depending who won.
So it would be interesting to see if Mr Turnbull turned up in a black tie.
"I would have turned up with a green and gold one if we'd lost."
Mr Key was joined at the game by Sports Minister Jonathan Coleman and Trade Minister Tim Groser who last week accompanied him to Brussels where discussion towards a free trade agreement began.
Labour leader Andrew Little was at Twickenham too in a private capacity but caught up briefly with Mr Key and his party after the victory.
Mr Little said he was sitting in front of the coaches and said the atmosphere has been fantastic.
"Clearly a lot of the English and other supporters had got in behind the All Blacks."
Mr Little said that after the results of the cricket and netball world cups earlier this, it was good the All Blacks had evened the score.
Richie McCaw was a world class captain who should be appropriately recognised and Dan Carter would go down as one of the greatest ever first five-eighths.
The Green Party congratulated the All Blacks saying the team had represented the country exceptionally well.
"We are so proud of this team, and everything they've accomplished so far," said MP Kevin Hague.
"Rugby is our national game and there's nothing quite like the camaraderie created by the whole country waking up at the crack of dawn to watch the All Blacks."
New Zealand First leader Winston Peters said his party would be moving a motion in Parliament on Tuesday congratulating the team.
