The next instalment in the More Joyous saga will be played out on Tuesday when Gai Waterhouse fronts an inquiry over whether the mare had a health issue before the Queen of the Turf Stakes.

The trainer has appealed a $5000 fine for not reporting More Joyous had a problem before the All Aged Stakes on April 27 in which she finished second last.

In a post-race interview, the mare's owner John Singleton launched his infamous public tirade against Waterhouse and sacked her as his trainer.

He also accused her bookmaker son Tom Waterhouse of revealing inside information to his Network Nine colleague, rugby league commentator Andrew Johns, that the mare could not win, sparking the inquiry.

Tom Waterhouse was cleared of any wrongdoing and Singleton was fined $15,000 for misconduct.

Waterhouse maintained throughout the inquiry there was no issue with the mare that warranted reporting to stewards and More Joyous was cleared by the stable's and Singleton's vets before the race.

During the inquiry it emerged More Joyous was lame in the lead-up to the Queen of the Turf on April 6 in which she finished an unlucky fifth, 1-1/2 lengths from the winner Appearance.

"We will be asking whether the condition of More Joyous before the Queen of the Turf should have been reported," Racing NSW chief steward Ray Murrihy said.

Trainers are obligated to tell stewards of any issue with a horse such as missing trackwork which may affect its performance on race day.

Although More Joyous was given the OK before the All Aged Stakes, stewards said they should have been made aware she had been treated with an antibiotic so the Racing NSW vet could also inspect her.

The winner of eight Group One races and more than $4.5 million prize money, More Joyous has been retired and will be served by champion racehorse Frankel in England in September.