He paid tribute to his mentor whose experiences - from his early days on a rural cadet scheme to his stint in Boston at Harvard, charity interests and professional directorships - shaped a rare man.
"Leadership's about trust and Wilson had a bucketload of trust.
"I think he understood people [from] all walks of life, all different New Zealanders ... I believe he was born a leader," Sir Brian said.
Sir Wilson's son James spoke on behalf of Lady Elisabeth and the family. He said his father enjoyed doing the small things with his family - turning up to their sports games or school events, first with his three children and then five grandchildren.
Close family friend and neighbour Dr Tom Marshall had the crowd chuckling when he told of Sir Wilson's competitive gardening streak and wonky attempts at wine and liqueur making - both went to a teetotaller who used the alcohol to clean paintbrushes.
Outside, family pallbearers carried the casket through an honour guard of junior rugby players. On the sunny cathedral forecourt mourners mingled and shared stories after the hearse pulled away.
Others at the service included last year's World Cup-winning coach Sir Graham Henry, Foreign Affairs Minister Murray McCully, New Zealand First leader Winston Peters, Olympic gold medallist Sir John Walker, Lady June Hillary, teenagers from Dilworth School, Victoria Cross winner Willie Apiata and business leaders.
The commanding officer of the Special Air Service, who declined to be named, said Sir Wilson was the inaugural chairman of the SAS Trust, which helps families of soldiers killed or wounded.
He said the SAS family would miss a wonderful friend who exemplified service to others and humility.
"Sir Wilson is a man who is beyond compare ... He spoke from the heart with a great deal of mana. He helped other people and had a strong depth of character ... those are the things that set a leader aside whether he's a military person, a leader in business, a leader in the community and Sir Wilson was all of those."
The CO joked that Sir Wilson would have made a decent fist of being an elite soldier: "I think had he turned his mind to it, he would have given it a damn good crack like everything else."
Auckland Grammar School old boy Barry Baxter, 78, played in the school's First XV with Sir Wilson. He said the occasion wasn't a sad one, rather it was a chance to remember the fun they had together.
"There were about eight or 10 of us in the First XV [who would] go to the Mount every Christmas and play and dance and swim and chase ladies. He was a great guy even then."
The Dean of Auckland, the Rev Jo Kelly-Moore, reminded mourners Sir Wilson had helped with the final fundraising to build the cathedral's nave. The 77-year-old's life should be celebrated for reaching so many, she said.
"The final whistle has sounded but ... extra time is for eternity."
