Retired bookmaker and hobby breeder Michael Thomas heads to Randwick with two chances in Group One races, something he almost let slip away.

After a couple of years breeding from Busking, Thomas sold the mare before later buying her back when Darley decided to move her on.

The mare was in foal to Teofilo with a colt who would later become Happy Clapper whose popularity in Sydney is surpassed only by Winx.

The Pat Webster-trained Happy Clapper runs in Saturday's Doncaster Mile while Busking's 2015 foal by Not A Single Doubt is named Not A Single Cent and runs in the ATC Sires' Produce Stakes (1400m) for trainer Ciaron Maher.

A dual Group One winner this season, Happy Clapper has been runner-up in the past two Doncasters and will have his work cut out again against a couple of lightly weighted colts.

Not A Single Cent won the Group Two VRC Sires' Produce Stakes (1400m) at his second start for caretaker trainer Aaron Purcell but has drawn the outside barrier in a field which features Golden Slipper runner-up Oohood.

"I'd never won a Group One race until the Epsom with Happy Clapper," Thomas said.

"He's now won two and has been advantaged this season by the addition of blinkers and the dry tracks.

"And he has been sparingly raced. He gets a lot of individual attention from Pat which is one of the reasons I sent him there.

"I wanted my horse trained at Randwick but not in a factory and Pat fits the bill."

Owner and trainer don't always agree but Thomas says Webster always gets his way.

Webster was training Thankgodyou'rehere, a multiple stakes winner, when Thomas decided five years ago to send him to Victoria where water walkers were coming into vogue.

To placate his trainer, Thomas said he could have Happy Clapper who is the second favourite for the Doncaster behind Godolphin colt Kementari.

Not A Single Cent is at $12 for the Sires' Produce Stakes and, like Happy Clapper, he will be ridden by Blake Shinn.

If he can win, he will give Maher a Group One welcome back with the trainer resuming operations at Caulfield this week after serving a six-month suspension over the bona fides of five horses in his stable.

"Ciaron picked him out at the sales and bought him on spec and I went to him and asked if I could buy back into him so I have 25 per cent," Thomas said.

"He is a horse I think will get at least 1600 metres."

Thomas describes himself as a recreational punter these days and has never backed Happy Clapper and never needed to with the gelding earning more than $4 million.