Observers said McMillan's triumph followed a remarkable effort in the trying conditions of his run on the opening day, hitting the top of the leader board and staying there despite the efforts of more than 150 dogs and their handlers in generally improving conditions over the following four days.
Brought-up on a family farm at Ridgemount Rd, McMillan had two wins in Hawke's Bay club trials earlier this year, with Base in the straight hunt at Patoka, where they were also third in the centre runoff, and with Gin in the straight hunt at Petane.
Last week's championships and the few days afterwards were major moments for the sport and two of its many genuine stalwarts.
The first was the New Zealand short head and yard victory by 70-year-old host Omarama club patron Ginger Anderson with Don, just after being made a life member of the New Zealand Sheep Dog Trial Association.
The second came as 73-year-old Poverty Bay stalwart Merv Utting, well-known in Hawke's Bay and whose service to the sport was on Monday recognised in the Queen's 90th Birthday Honours by being made a Member of the New Zealand Order of Merit (MNZM), aptly making-up for being unsuccessful in his bid to defend the title he won last year at Moawhango, near Taupo.
It was Anderson's latest national title in a top-level career which dates back to almost 50 years to a South Island Championships runoff in 1967.
Utting has won six national titles in the 42 years since a North Island championships runoff in 1974.
King Country trialist Hamish Parkinson, of Owhango, had a successful trip south, claiming both the national and South Island zig zag hunt titles with Shake, in what were only his second and third runoffs at that level, while Northland competitor Murray Child and Dice added the national long head title to the North Island championships long head title they won last month.
It was Child's 4th national title, and a second for the trusty Dice.
The six days of championships had more than 200 runs in each of the South Island classes.
Next year's New Zealand Championships will be held with the North Island championships in Poverty Bay, while the South Island Championships will be held in Otago.