The 15-year-old could not have had a bigger smile on a face as he watched the first horse he purchased and is sole owner of - Harry Croft - win at his home track.

Jett's father Nathan Turnbull, who was in the gig, let out a loud 'woooo' in celebration as they headed towards the winning post, the rest of the field almost 25 metres behind him.

"I did that because I knew the big fella [Jett] was here, as soon as I looked around after the line all I could see was his big smile. That's what it is all about," Nathan said.

"I am so proud for him to be as interested as he is, he just loves it. That he wants to follow in my footsteps is just great.

"It won't be good enough just getting winners now, he'll want to own them all," he added with a laugh.

The win a big moment for the teenager, who is part of the fourth generation of one of New South Wales' largest harness racing family dynasties.

Jett's great grandfather, the late Tony 'AD' Turnbull, was arguably the most decorated horseman in the history of the sport as he not only won the Miracle Mile and Inter Dominion, but in 1990 received the Order Of Australia Medal and in 1998 was made Harness Racing NSW's inaugural Living Legend.

Then there's his grandfather Steve Turnbull, who has trained more than 4,000 winners and notched up in excess of 3,000 victories in the gig.

As for his father Nathan, he's just put together the biggest season of his career as a trainer-driver.

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Naturally Jett grew up around horses. In 2016 he became the first person to successfully complete the Harness Racing NSW Stable Awareness Course.

That meant he was permitted in the stable area under parental supervision - something which was otherwise prohibited for children under 14 at trials and race meetings.

"Back then he kept getting kicked out of the stables because he was too young, but he was that interested we couldn't turn the kid away," Nathan said.

Since completing the course Jett has become a regular in the stables. He is also working towards driving at race meetings himself - something he'll be permitted to do in July when he turns 16.

No doubt given what six-year-old gelding Harry Croft did on Friday night in his second start for Jett, he'll own more horses in the not-to-distant future as well.

"It's the first one he owns outright. He went to Queensland and he drove it in a trial up there. I asked him 'How did it go?' and he said to me 'It didn't do much'," Nathan revealed.

"Then the next day he rang me and told me 'I bought that horse.'

"I was like 'I thought you said it didn't do much', but he told me that it would be right and I'd win with him, he's pretty low graded.

"He's put a lot of faith in his trainer," Turnbull laughed.

When Jett purchased Harry Croft his record stood at 10 wins and 26 placings from 94 starts.

But since joining Nathan's team he's notched up a second at Junee then the win at Bathurst on Friday.

His success at Bathurst came over 2,260 metres as a the $2.80 favourite.

While he was caught three wide early, Nathan kept the gelding going and had the lead as they hit the mile marker.

Down the back straight for the final time Switchem All In got with a neck of him, but with around 450m to go Harry Croft left his rivals in his wake.

He went on to win by 24.8m in a career-best 1:58.6 winning mile rate, Alpha Xena ($16) the best of the rest.

"He went out there the other night [at Junee] and we learned a bit, he was a bit one paced, they went straight past him and it was like he was going to run nowhere, but the just kept plugging along and ran into second," Nathan said.

"So over the longer distance, I knew I had one mission, keep going. That's why I kept the pace pretty honest, didn't give him a breather."

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