Chris Waller is working an angle connected to one of the modern era's greatest race mares to lock in an Epsom Handicap-Cox Plate bid for Royal Descent.

Second favourite to win the $500,000 Epsom Handicap, Royal Descent is owned by Gerry Harvey, a man who has become one of Australia's wealthiest retailers by being the consummate salesman.

But when it comes getting Royal Descent to the Cox Plate in the best possible shape, it is Waller who has been the persuasive one.

Combining an appreciation for racing's history with a sense of opportunity, Waller has convinced Harvey his high-quality mare should have her final Cox Plate lead-up run in the famous Randwick mile on Saturday.

It sets Royal Descent on the same path Sunline took before the first of her two Cox Plate triumphs in 1999 as well as the one that delivered victories for two more mares - Dane Ripper in 1997 and Pinker Pinker in 2011.

Although they couldn't win the Epsom, Waller didn't have a moment's hesitation pitching his plan to Claire Bird, Harvey's racing manager who made a name for herself as the strapper of Sunline.

He said Royal Descent's spring had been be tailored to have the ATC Australian Oaks winner in the same form in Melbourne as she has been in Sydney.

Royal Descent has been runner-up at her past three weight-for-age starts including the Group One George Main Stakes in which she was beaten by Sacred Fall, another Waller star who is one of the Cox Plate favourites.

"I don't think she needs hard racing and that mile will just top her off with three weeks to the Cox Plate with just a couple of Moonee Valley gallops in between," Waller said.

"Had I run her in the Turnbull Stakes and then given her some of those tough Moonee Valley gallops as well there's a chance of over-training her.

"There's a Claire Bird-Sunline connection there with Royal Descent and Gerry Harvey and it wasn't hard to sell the option to them."

Royal Descent will be one of four Epsom runners for Waller with last year's winner Boban, the well-supported He's Your Man as well as Lucky Chappy confirmed starters.