Douglas Whyte is poised to capitalise on the unavailability of three Hong Kong jockeys' room rivals when he rides Moriarty in the Kingston Town Stakes.

Whyte snapped up the Group One ride at Ascot on Saturday when Zac Purton and Joao Moriera couldn't answer an SOS from trainer Chris Waller after Nash Rawiller's Hong Kong suspension ruled him out of the $500,000 race.

"We've built up a bit of a relationship with a few of the Hong Kong jockeys and I'm sure Douglas will do a great job for us," Waller's racing manager Liam Prior said.

"He rode in Perth last year so he knows the track."

Rawiller rode Moriarty when the veteran made a late impression to take the minor placing in the Group One Railway Stakes.

It was the seven-year-old's first outing since finishing worse than midfield in the Mackinnon Stakes and bookmakers saw enough merit in the run to make him a $4 favourite to give Waller his 10th Group One win for 2014.

"Initially we were fifty-fifty as to whether we went to the Railway and to see him stretch out like he did over the mile ... it's full-steam ahead for Saturday," Prior said.

Whyte rode the Waller-trained Junoob in the Caulfield Cup and left a lasting impression on Sydney's premier trainer.

"While he didn't win the race for us, everything from his feedback to his preparation for the race, I know Chris was taken aback," Prior said.

Waller linked with Purton for Doncaster Mile and George Main Stakes wins with Sacred Falls this year, while he teamed up with Moreira to claim the Epsom Handicap with He's Your Man.

Moriarty has lined up in nine Group One races during an Australian career that started in 2012, netting 10 wins and most of the stayer's $1.36 million in stakes.

"He's raced at a high level for well over 12 months now and has raced competitively in Group One races," Prior said.

Bookmakers rate WA Guineas runner-up Disposition ($6.50) as the main threat to Moriarty while Railway Stakes winner Elite Belle is a $7.50 chance.

Pheidon ($11) and Smokin' Joey ($14) complete the eastern states' representation for Australia's last Group One race of the year.