"He's been a model of consistency throughout his career and [jockey] Glyn Schofield has been a part of that.
"The horse was just in his own comfort zone and happy in his own space and he was strong."
Prized Icon ($17) was 2 lengths too strong for the Kiwi Sacred Elixir ($2.70 favourite), whose trainer, Tony Pike, was disappointed, believing he had hit the front too soon.
Schofield timed his run perfectly.
"I told James when (Prized Icon) won the Champagne Stakes in the autumn he was a Derby horse, and it doesn't always work out but it did today," Schofield said
Pike said Sacred Elixir would bounce back for a Sydney autumn campaign.
"He possibly over-raced a couple of times in the run but not too badly," he said. "He might have got there [lead] far too soon.
"Zac, I think, was worried about getting held up by the horses coming around him three-deep.
"He had a decent old bumping duel with it on the corner, and both him and Swear probably landed in front together at the top of the straight and he had to sit and wait for a fair while.
"But he's probably better just coming into it the last couple of hundred metres.
"That's it for him this prep. He'll go home and have a spell and head to the Championships in Sydney."
The winning trainer was surrounded by family, including his father, Anthony, who trained the 2012 Victoria Derby winner, Fiveandahalfstar.
James Cummings trained in partnership with his grandfather Bart until the master trainer's death in 2015.
Bart Cummings trained five winners of the Victoria Derby and his father, Jim, trained one, Comic Court, which won in 1948 and went on to win the Melbourne Cup.
That race is unlikely for Prized Icon, who is raced by Eduardo Cojuangco, the grandfather of James' wife, Monica.
Anthony Cummings was also on hand to celebrate the win after a tough couple of days in which a family dispute over his later father's will became public.
"I'm very proud," he said.
"It's a great thing. Four generations and still going. It's only early days yet.
"James has made a great start to his training career and continues on the family name."
There were few excuses for the beaten brigade, with Inference (9.50) 1 lengths from Sacred Elixir, and many of the others struggling to run the 2500m.
