After experiencing the highest of highs and deepest of lows at Ellerslie over the years, on Saturday Trudy Thornton will be on a mission to claim one of racing's biggest prizes at the country's premier track.

The 58-year-old, who began her career as an amateur jumps jockey in 1982, is set to ride Arjay's Flight in the Group 1 Vodafone New Zealand Derby (2400m), confident he has the credentials to shake off his maiden status in style.

The Mark Brosnan-trained gelding brings impressive form into the classic – a last-start second to La Crique in the Group 2 Avondale Guineas (2100m) on top of a fourth placing in the Group 2 Waikato Guineas (2000m) and third in the Listed Gingernuts Salver (2100m).

Thornton has ridden Arjay's Flight in each of those races and believes his form is as good as any amongst the 12 geldings standing in the way of the only filly in the field, odds-on favourite La Crique.

“He's a dude of a horse and his form really does stack up; I just feel lucky to be his Derby jockey,” Thornton said.

“I'm sure a lot of others have tried to get on him, but I'm fortunate to have Mark Brosnan and his wife Yo along with the owners in my corner.

“I've been around this game long enough to know that loyalties are few and far between, but in this case I've got people who have stuck with me, and I'm very grateful for that.”

Thornton's formative years were quite different to what followed, beginning with an amateur licence before embarking on an apprenticeship.

Her early brief included riding over jumps – she was the first woman to compete in the Great Northern Steeplechase – before establishing herself as a natural lightweight who is still able to ride comfortably at 51kg.

Thornton's first Group One win came at Ellerslie on Pakaraka Star in the 1995 Easter Handicap (1600m), and her last two Group Ones have also been there, Authentic Paddy in the 2017 Zabeel Classic (2000m) and Santa Monica in the 2019 Railway (1200m).

The closest she has come to winning the New Zealand Derby was on the Roger James-trained Corndale, who was beaten a short neck by Surfers Paradise in 1990.

A week later she was again narrowly beaten on Shugar in the Auckland Cup by the longshot Star Harvest, ridden by her then husband Jim Collett.

But while Ellerslie has provided Thornton with a number of career highlights amongst exactly 200 wins there, the track has also been the scene of catastrophes that may well have ended the career of a lesser mortal.

At a November 2008 race meeting her open 1600m mount The Cosmob collapsed with an internal haemorrhage, and only quick work by the starting gate attendants, who had witnessed the incident some 500m further up the back straight, saved her.

When they arrived at the scene, the dead horse was completely smothering Thornton, however by brute strength the attendants were able to roll the horse off the hapless jockey, who was unconscious and not breathing.

Further quick work by ambulance personnel, who administered oxygen, aided Thornton's recovery and incredibly when she was taken to hospital for observation, her only injuries were bruising to her liver and spleen as well as general soreness.

In April 2014 at Ellerslie, Thornton hit another major hurdle in her career when she broke a hip in a spectacular fall, initially having plates and screws inserted but eventually having to undergo a full hip replacement to enable her to resume riding.

Thornton's 40 years in the saddle, which have netted more than 1,150 wins, have also been punctuated by the birth of three children, the eldest of whom is now Queensland-based premiership-winning jockey Samantha Collett.

Later this month the Ellerslie track will be closed for a major renovation and by the time it reopens in late 2023, Thornton will be 60 years old. But that's hardly going to stop the woman who takes determination to another level.

“Of course I'll be back with everyone else when Ellerslie starts up again,” she said with a touch of indignation. “I love riding there and after all, what else am I going to do?”

For the meantime though, Thornton's focus is Derby Day and the race she would dearly love to win.

“I have a lot of faith in Arjay's Flight; he's had the right preparation, he has a good gate and from there I'd like to think I can track through somewhere behind the favourite.

“Just so long as he gets his chance – you can't ask for more than that – and the rest comes down to whether you're up to it on the day.”