Trailing 13-time champion jockey Whyte's record haul of HK$1,587,210,086 – accumulated from 1,813 wins – Purton started the meeting HK$1,210,620 in arrears of the South African but the Australian closed the day in style with victory on Tony Cruz's Beauty Joy to win the Class 3 Tourmaline Handicap (1400m) and set a new mark of HK$1,588,025,566.
Beauty Joy was the second leg of Purton's double after Benno Yung's Millennium Falcon's enabled the Australian to lay the platform for a successful chase by landing the Class 4 Onyx Handicap (1400m).
With 1,341 career wins in Hong Kong, Purton leads the 2021/22 championship with 46 victories – 10 ahead of Joao Moreira – as he chases a fifth title.
Purton diplomatically downplayed the prizemoney achievement, but there is little doubt he still has unfinished business in Hong Kong.
"It's another nice milestone to hit," Purton said. "It's another nice record to put on the CV, it feels good but there's still work to do. Since I've been in Hong Kong and that's been nearly a decade and a half now, prizemoney has gone up about 3-5 percent every season, so we're obviously racing for a lot for money these days.
"I've been very lucky in my time here in that I've ridden a lot of good horses, I've won a lot of big races and they obviously help towards to the total."
Purton said Whyte's record haul of wins remains a target.
"I think 1,800 wins is gettable. By the time I get to the end of this season, I should be at 1400 and it's not too far away from there. It gives me something to think about, anyhow," he said.
On a day of milestone triumphs, Lyle Hewitson and Victor Wong notched their first winners of the season as John Size continued an ominous march towards a record 12th trainers' championship with a treble.
In a welcome case of déjà vu, Hewitson teamed with Douglas Whyte to log the first victory in his second Hong Kong stint aboard Valiant Elegance in the Class 4 Kowloon Tong Club Trophy Handicap (1200m, dirt).
Hewitson and Whyte combined in December, 2019 with Last Kingdom when Hewitson needed 141 rides to get off the mark in his first Hong Kong sortie. The South African was much quicker this time, taking only 14 mounts to prevail – and again in tandem with Whyte.
"It's very similar. It was also on the dirt, I also led start to finish and just held on at the end for the Whyte stable. The biggest difference this time is that it was three meetings into my stint, not three months, so obviously I'm very glad about that and I'm just grateful," Hewitson said.
"It's not easy to give a rider support when maybe the form book doesn't suggest it, but Dougie fortunately has stood by me and given me this chance. I'm just happy it's all worked out and I'm happy to be on the board early and I look forward to the next couple of years, hopefully."
Whyte believes Hewitson has what it takes to succeed on his second stint in the jurisdiction.
"He's a lovely individual, he's got a great style, he tries his best but Hong Kong can be a hard place," Whyte said. "But, he's hungry. He comes in early in the morning and he rides work for me. He's there for the first lot, so it's nice to give the guy an opportunity.
"It was a heady ride. It looked easy, but it wasn't. The horse is not straight-forward. I hope this just gives Lyle a bit of a foundation now to move on and get some more support because he's here hopefully for the long term. Let's hope this is a stepping stone for him."
Hewitson's win is a timely boost for the 24-year-old who will represent South Africa in Wednesday's LONGINES International Jockeys' Championship.
The South African's triumph preceded Victor Wong's upset success on Ricky Yiu's Alcari in the Class 3 Opal Handicap (1000m), the home-grown jockey's maiden winner of the season.
"It's very satisfying," Wong said. "The horse was dropping back 200 metres in distance but he did a great job. I'm very happy to have won. I just need more opportunities. I'm working hard, I just need more rides."
Size continued his stunning surge to climb into third place in the trainers' championship behind Frankie Lor (26) and Tony Cruz (19), with 15 of the 11-time champion Size's winners arriving in the past two months.
"The horses are running well. The cooler weather, they appreciate that I suppose," Size said after the triumphs of Sight Success, Amazing Teens and Country Boy.
Vagner Borges is one of the beneficiaries of Size's onslaught, sharing a double with the master trainer by piloting Amazing Teens to victory in the Class 4 Amber Handicap (1800m, dirt), overtaking Joao Moreira and Toycoon in the closing stages.
The Brazilian sealed a double with with Size's Sight Success' devastating victory in the Class 2 Carbine Club Of Hong Kong 30th Anniversary Cup (1200m, dirt).
"It's fantastic to ride a double and I'm very grateful to be able to ride for Mr Size. The support is great," Borges said.
Six of Borges' eight victories this campaign have come in tandem with Size, who also partnered with Frenchman Alexis Badel to snare the Class 4 Garnet Handicap (1200m) with Country Boy, a four-year-old son of Shamardal.
Matthew Poon posted a double, initially rewarding Michael Chang's persistence with Speed Force when the Hong Kong International Sale graduate cruised to victory in the Class 5 Jasper Handicap (1650m, dirt). Placed in only one of his previous 21 starts, the Camacho gelding triumphed with surprising ease.
Poon completed the brace with Frankie Lor's Infinite Power in the Class 3 Peridot Handicap (1650m, dirt), to boost his personal tally for the term to nine and Lor's to 26.
Peter Ho's Chunghwa Jingshen prevailed after an inspired ride from Dylan Mo to land the Class 5 Aquamarine Handicap (1200m, dirt). It was the gelding's second victory from 22 starts.
Hong Kong racing continues at Happy Valley on Wednesday (8 December) with the staging of the LONGINES International Jockeys' Championship.