When Lancaster stepped into the middle of the wreckage that was English rugby on December 8 last year, few could have envisaged a result or a performance like it.
Even on Saturday morning, it was a stretch given the All Blacks were on a 20-Test unbeaten run and England were beginning to feel the heat after successive defeats to Australia and South Africa.
But Lancaster's callow team delivered one of the great England displays. The All Blacks, who some have called the best team ever, could not live with the thunderous intensity.
Owen Farrell kicked England into a 15-0 lead before their character was tested when the All Blacks hit back with two converted tries in three minutes.
England's response was emphatic. Brad Barritt, Chris Ashton and Manu Tuilagi scored in quick succession before Freddie Burns came off the bench to kick two penalties on his debut.
While deservedly proud, Lancaster also stressed the need for England to use this victory as a launchpad for the Six Nations and beyond to the 2015 Rugby World Cup.
"It's the highest point, isn't it? We've played the world champions, who were unbeaten in 20 matches, and we've put in a performance that has beaten them fair and square," Lancaster said.
"To put that type of performance under that sort of pressure after the scrutiny of the last two weeks, is fantastic really.
"It was less than 11 months ago we changed the direction of travel for England rugby, to build a team for the future but also wanting to win in the here and now.
"Sometimes it takes a win to show that and the most pleasing thing is it has given a clear view of the direction we are going.
"We have got to make sure we back up now. As a coaching team we're far too pragmatic (to allow anyone to think we are the finished article) - and I'm far too Cumbrian to allow that to happen.
"I'm already thinking how we're going to plan for the pre-Six Nations camp in Leeds and how we're going to maintain this standard.
"We've got to make sure we hit that level in Six Nations."
Lancaster took the decision, initially as interim head coach, to cut adrift the experienced players who had failed at the World Cup and rebuild the England side.
Seven of the starting team that beat New Zealand were only capped this year. Chris Robshaw had made just one previous England appearance when he was named captain before the Six Nations.
The new band of brothers went on to finish second in the championship, beating France in Paris and then Ireland at home. It was a glorious honeymoon period.
Reality began to sink in during the summer tour of South Africa, when the Springboks won the first two Tests before England rallied to draw the third.
Back on home soil in the autumn, England were shown up as being naive in the 20-14 defeat to Australia and were then edged out 16-15 by South Africa in a game they should have won.
It is those experiences, not just his Cumbrian roots, that will keep Lancaster grounded over Christmas. That and the fact he is back coaching the West Park Leeds Under-12s this week.
But equally there is much to be excited about.
Joe Launchbury and Tom Youngs have excelled for England this autumn, while Jonathan Joseph and Freddie Burns could have big international futures.
"I've never doubted the direction we're going," Lancaster said.
"Rugby's fairly simple. If you get a good culture, a good environment, good players, good coaches and if you work hard enough you'll get results.
"I believe in the players we've got. We have lads like Joe Launchbury and Jonathan Joseph and Owen Farrell and Freddie Burns who are 21, 22 and 23 years old.
"They should be playing for England for years and we should be sat here in 10 years' time and still have the same group of lads with 800 caps (instead of 206) in our starting XV.
"And we've got good players to come back into the equation for the Six Nations, like Dylan Hartley, Tom Croft and Ben Foden.
"The coaches are outstanding. The environment we've got is a strong one and it held together under pressure and we kept believing. To get that scalp is a fantastic scalp."
Crucially, England kept believing on the field at the key point in the game, just after the All Blacks had closed the gap to 15-14.
"That did test us and the way we responded showed that we've learnt," Lancaster said.
"The 15-0 half-time score was fantastic. Sure they'd missed a couple of kicks which was uncharacteristic, but you take that. Our forwards had the edge and we talk about pressure defence.
"Even after that resurgence, our composure and our intent to keep playing was there."
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