Shrimpton's racing outfit not forgotten

That white mini-dress, no stockings, no hat and no gloves - all in the members' area at Flemington racecourse, no less.

There has never been such a defining moment in Australian fashion than Derby Day 50 years ago, when international model Jean Shrimpton caused jaws to drop among the conservatively dressed members.

Vogue Australia editor-in-chief Edwina McCann said Australians in 1965 were outraged, while people in Paris and London wondered what all the fuss was about.

"It was one of the biggest moments in Australian fashion history, but without doubt one of the bigger moments globally as well," McCann told AAP at Derby Day on Saturday.

"The '60s were redefining our society and that fashion moment was able to communicate that in one photograph."

Fashion designer Dom Bagnato loved "the Shrimpton moment".

"I just love these moments that define our time," Bagnato said.

"It was a beautiful moment because it did cause a massive attitude change towards how women dress in general, not just to the races."

Shrimpton, then the world's highest-paid model, returned more conservatively dressed on Cup Day.

McCann said there was a clash of generations.

"Some people really admired what she'd done. I think the younger teenagers, for example, thought, 'Wow, we're finally modernising fashion in Australia.'"

There was another "moment" of sorts when "it girl" Paris Hilton turned up to the 2003 Melbourne Cup looking more like she was going clubbing than to the races, in a blingy, skimpy top.

"That was a moment where we went, 'Hang on a minute, race wear is more like beachwear or nightclub wear and we need to recalibrate things again,'" McCann said.

As for the trend this year, Bagnato said it is all about colour, even for men.

"I don't think we've seen as much colour as we're going to see through the carnival since the '70s," he said.

"I'm seeing that in men's as well - this will be the most colourful carnival for menswear that we've ever seen."