''He [Avebury] has been in the right place at the right time," a delighted Nicholson said.
''He's always been a winner and horses that are consistently winning have a chance to do what he's done. This means an awful lot."
Paget won Burghley last year on Clifton Promise but when the horse failed a dopinig test lost the title and the rider was provisionally suspended. That punishment was lifted just a few weeks ago, along with a clearance of any wrongdoing on Paget's part.
''You draw your confidence from the horse you're sitting on and in the warm-up he was giving me a really good feeling," Paget said.
''Had he been booting the fences down outside you might have seen me with a different expression on my face."
The only other New Zealander combination of the seven who began the final four star event of the season, Jonelle Price on The Deputy, also completed a clear round to finish an impressive ninth.
"It is just an amazing feeling," he said. "I have the easy part. Avebury is such a special horse."
Waikato horseman Nicholson was quick to praise others in his team for their part in the horse's success, including grooms, vets and wife Wiggy.
''This is a very special moment. I have had a bad year and was putting a whole lot of pressure on myself."
Nicholson took the lead during a gritty cross country round 24 hours earlier, but says he was not complacent going into the show jumping.
"Eventing is very much three phases, and I know he is good at all three. I just have to do my job properly."
Nicholson has now won Burghley five times, starting in 1995 on Buckley Province and following that in 2000 on Mr Smiffy.
He equals the record of Mark Todd, who also has five wins at Burghley. It is the 13th win at Burghley by a New Zealander, adding two victories for Blyth Tait in 1998 and 2001. Caroline Powell also won the event on Lenamore in 2010.
Nicholson also finished fourth in the 2014 FEI Classics list after this season's six events, with Tim Price fifth and Paget ninth.
Jonelle Price's performance jumped her to third place on world rankings, behind Britain's William Fox-Pitt, who finished fourth at Burghley, and Nicholson.