Brothel owner Eddie Hayson says former rugby league great Andrew Johns never discussed the health of racehorse More Joyous with him when the pair spoke at the footy.

Hayson was giving evidence at a NSW stewards' inquiry into allegations surrounding the performance at Randwick last month of the champion mare owned by John Singleton and trained by Gai Waterhouse.

Singleton has accused bookmaker Tom Waterhouse of telling people the horse could not win the All Aged Stakes after receiving information from his mother Gai.

More Joyous ran second last in the race.

Hayson told the inquiry on Monday that Johns had more likely told him the horse wasn't "fancied" or that Tom Waterhouse had said it "can't win".

"I can't recall the exact conversation but it wasn't pretty," he said.

But by race-time, he had heard worrying reports about More Joyous from two other sources, and had relayed his doubts to former jockey Allan Robinson.

"(I said) I heard the vet's been over it all week, and it wasn't eating," the big-betting brothel owner told the stewards.

"He said, 'That just doesn't sound right, there's no way Singo would run a horse that had something wrong with it. I'll ring him and clarify'."

Hayson said he was keen to learn of the outcome of the race, even though he had decided not to have a punt.

"It did sound as if everyone knew the horse couldn't win except Singo," he told the stewards.

He refused to publicly name the sources who told him about the health of the horse - but said the information he gleaned led him to decide he "wasn't going anywhere near it".

He also denied he was trying to embarrass the Waterhouse family by speaking out to Robinson.