On a sunny autumn afternoon amid a typically brash and glamorous Sydney party, a young man with a heavy heart was hard at work, building a remarkable legacy.

Race day at Randwick is always a triumph of glitz and glamour, with the action and distraction off track often overshadowing the competition on the turf.

But 23-year-old Tommy Berry won punters hearts as he crossed the finish line a winner three times, little more than two weeks since the sudden and tragic loss of his twin brother and fellow jockey Nathan to illness.

"Every race I win for the rest of my life is going to be for Nathan," a close-to-tears Berry said after riding the Gai Waterhouse-trained The Offer to victory in the 3,200m Sydney Cup, securing a $600,000 prize.

"He's my best mate, he's my best support and I'll never be able to replace him."

It was a fitting finale for The Championships - the two-day, $18 million racing carnival introduced to steal some of Melbourne's racing glamour back to Sydney.

More than 25,000 people flocked to Randwick for the day, among them Prime Minister Tony Abbott, accompanied by his wife, Margie and his parents for a lavish lunch in a private dining room.

The headline event was the $4 million Queen Elizabeth Stakes - now the richest 2,000m turf race in the world.

Queen Elizabeth herself had a horse in the race - Carlton House - and her grandson Prince William, currently in Australia, was originally to be on hand to congratulate the winner.

Mr Abbott took the prince's place and in the end the Queen's horse ran third to favourite It's A Dundeel.

The Championships marks a new era in Sydney racing and, after a rain-soaked day one on April 12, delivered on Saturday with hordes of happy punters.

Canadian Robin Derkatz, 25, said she was amazed by the atmosphere, which was unlike anything she had seen in the racing scene back home.

"We don't really celebrate it this way in Canada - no one wears fascinators and dresses up," she said.

About 750 Sydneysiders paid up to $695 a head for entry to the exclusive Little Sydney enclosure, which featured marquees by four top local restaurants.