Jones was the runner-up in the 2017 competition and "definitely dressed to win" this year in a second-hand soft tulle dress she found on Facebook. It worked.

The registered nurse and fashionista impressed Fashions on the Field judges with her muted colour palette, a stunning Moore Millinery Designs hat and vintage handbag from The Iconic.

Jones and 5000 Canberrans flooded through the gates of Thoroughbred Park on Tuesday for the running of the TAB Federal and a front-row view of the 2018 Melbourne Cup on the big screens. Five-year-old mare Ons Vier, trained by Joe Ible, took out the main race of the day - the $50,000 Federal.

But trackside, Jones was definitely a stand-out in the sea of tiny lace dresses, beaded headbands and sky-high heels.

She spent three-and-a-half hours getting ready for race day at home in Yass, including a visit to Raven hairdresser on the main street of her hometown.

"I'm a regular at the races in Canberra and some of the country towns around Yass," Jones said.

"I love the races - it's fun, you meet new people and the fashion is divine - I love the dresses and the hats."

Aside from the sash and the glory, Jones' prizes for winning Fashions on the Field include a trip for two to Paris. She'll take her partner as a reward for "waiting patiently while I took so long to get ready".

Male Fashions on the Field winner Hamish Lardi warmed up for his big win by coming runner-up at Magic Millions on the Gold Coast in January.

He was inspired by "outfits my grandfathers used to wear" and wore a double-breasted linen suit, a boater hat (spray painted by talented Canberra milliner Jade Sargent from Sovata) and carried an umbrella to victory on Tuesday.

"If you're going to come to the race track there are certain etiquette rules - both male and female - and I think it's essential to dress your best," Lardi, an IT contractor to Defence, said.

"It's about dressing eloquently.

"I love race day. I feel in Canberra you don't get a chance to really dress up very often and it's one of those days that you definitely get to."

The Thoroughbred Park crowd was boisterous but happy, with ACT Policing confirming it was "generally happy" with the behaviour of patrons on the day.