They could run another 150 Melbourne Cups and never land a story like this.

The trainer, Darren Weir, a proud "bushie" whose dream when he started out was to win a Stawell Cup, a Ballarat Cup, a Swan Hill Cup – because that was the nearest neighbourhood track, just down the road from his Mallee home of Berriwillock – and almost as an afterthought a Melbourne Cup.

"I knew I was dreamin'," Weir said.

He's always been a man to have a go, since famously arriving for his first job as farrier at Terry O'Sullivan's stables on horseback.

"I was 18, had no money, hit a kangaroo out the road. It was a fair walk to Terry's place so I decided to ride a horse in."

Then there was the horse, Prince Of Penzance, purchased for the relative racing pittance of $50,000.

He came through two serious fetlock operations then survived colic and a twisted bowel, a dual affliction that demands an operation many thoroughbreds don't wake up from.

Up against rivals owned by Arab sheiks, American bankers, Japanese plutocrats and the odd Australian tycoon, this unspectacular six-year-old gelding swept all before him.

In lounge rooms, pubs and among the 101,105 who came to Flemington, once-a-year punters held a prized ticket aloft. They'd backed the winner of the Cup – at 100-1!

And then there was the jockey. For many their dollar each way was on the long shot simply because aboard Prince Of Penzance in the mauve and white checks, dark green sleeves and cap was the only female rider among the field of 24.

And now Michelle Payne is the only woman to have ridden the winner of a Melbourne Cup. That she shared it with her brother Stevie, Prince Of Penzance's strapper who has become a joyous beacon for the life those with Down syndrome can lead, added another rich layer.

Stevie Payne drew barrier one for the horse on Saturday night, and sent his little sister onto the track on Tuesday with the instruction, "Don't get beat – I've got my money on you!"

They've always looked after each other, the youngest two of a remarkable Ballarat family of 10 kids who lost their mother in a car crash when Michelle was just six months old.

Every day Paddy Payne was forced to live the advice he gave Michelle when a grumpy Shetland pony threw her off when she was just four. "Get back up or you never will."

Michelle thanked them all on Tuesday, and was especially warmed that all of her sisters were at Flemington – including Bernadette, who aged 11 amid a family's harrowing loss would get up in the middle of the night to feed her baby sister a bottle, then fall asleep at school the next day; and Therese, for whom Michelle would bring home a present when her classmates were allowed a $2 gift from the Mother's Day stall.

The eldest of Paddy and Mary's offspring was missing: Brigid, who died in 2007 after aneurysms and a heart attack that doctors believed was connected to a fall during trackwork six months earlier that left her in an induced coma.

Michelle knew her father would be proud as punch at home at the back of the Ballarat racecourse, where she rode her first winner for her trainer Dad at 15 and with her schoolmates cheering from the rails.

Seven of the Payne children took up riding and Paddy Payne was a hard judge of all. It steeled his youngest daughter, whose most vivid childhood memory is her father telling her every day how beautiful her mother had been, and how much he loved her.

When Paddy stopped the older Payne children from shooting Michelle and Stevie with slug guns, they turned their youngest siblings – who were inseparable and known simply as "the little kids" – into mock horses for hands-and-knees races around the rockery.

On Tuesday Payne had pearls in her ears, braids in her hair and eyes that sparkled like an angel's. The scars curling from her upper lip and across her forehead betrayed how tough her job is; at 18 she face planted off a horse at Sandown, fractured her skull and bruised her brain.

There have been other near catastrophes, and she's often spoken of getting out of the saddle by the age of 28.

Now, the prospect of having a dual training and riding licence when the initiative comes in next year excites her. "I'd always thought if I won the Melbourne Cup I'd retire," she said, already resetting her sights.

The manner in which she turned brother Stevie's $10 each way into a bonus that had him beaming all the more was emblematic of the way she used her historic platform to humbly and articulately profess her hope that this incredible win will make a difference in a sport where women still run a distant second to men.

"I feel that a lot of the time I get taken off because they say she couldn't get out or whatever, then the guys get on and do the same and they say, 'He was unlucky, he couldn't get out.' That just drives me crazy.

"A lot of the time I'm way more dedicated than a lot of those guys are because you get less opportunities [as a woman]. I try so hard in every race. It's just frustrating. I dunno whether it'll help, but I certainly hope it does."

Payne spoke of Joao Moreira's annoyance with her soon after Prince Of Penzance had missed the start, when she held her line as the Brazilian jockey tried to take her position. Here was the strength of mind she knows is underestimated.

Down the back straight her horse was strong on the bridle, pulling and throwing his head around. She looked across at Brett Prebble, who is married to her sister Maree, on Bondi Beach, so relaxed it might have been sleep-galloping. "I thought, 'Dammit!'"

On the victory dais she spoke of her craft not being all about strength, "it's also about getting a horse to relax for you, getting them to try for you".

Coming to the turn she hooked onto the back of Trip To Paris, couldn't believe how well her mount was travelling, found clear running and tried to wait. "When I let loose I've never yelled so loud in my life."

She'd ridden Prince Of Penzance in 22 of its 23 starts, but knew some of its owners were keen to replace her.

"Sandy might not have been my hugest fan," she said of Sandy McGregor, who two seats along passed the baton to another member of the syndicate, John Richards.

"We tossed over lunch – I got to choose the colours, John chose the jockey." Asked how he feels about Michelle Payne now, McGregor wasn't hesitating. "I'll put her on all of them."