Brian McGrath was always odds-on to be involved in the horse racing industry.

The 29-year-old saddles his first city runner and third career starter at Moonee Valley on Saturday after being licensed at the start of the season.

McGrath's path into racing was formed decades ago.

His grandfather, Brian, was a prominent Melbourne bookmaker during the 1960s and 1970s and his father is well-known British racecaller and journalist Jim McGrath.

After a stint on the racing desk at The Sun in London during his last year of university, McGrath wanted a more hands-on role.

It's taken him around the world and into the biggest stables, including stints as foreman for Robert Smerdon and Chris Waller after moving to Australia 3-1/2 years ago.

"I was born in Hong Kong and grew up in England but there's always been a connection with Australia," McGrath said.

"I was always attracted to Australia and the exciting racing and its booming industry."

Two-year-old Magnanimously, a daughter of Not A Single Doubt, makes her debut in the John Paraskevas Plate.

The filly has some heavy hitters in the ownership, including his father, Victoria Racing Club treasurer John O'Rourke and former AFL star and media personality Sam Kekovich.

McGrath said the filly deserved her chance in town against a field of first-starters but was a daunting task taking on trainers who are household names.

"This filly won a jump-out at Cranbourne," he said.

"She beat one of Robbie Griffiths' and they were a long way clear of the third horse and ran solid time.

"You have to respect Gai Waterhouse, the Hawkes family, Hayes and Dabernig and I was talking to Dad and saying look at all the names we're up against."