Trainer-jockey Johnny Murtagh believes Royal Diamond is in even better form now than he was a year ago as the admirable stayer prepares to defend his crown in the Irish St Leger at the Curragh on Sunday.

The seven-year-old clinched victory in a thrilling climax to the Curragh Classic last September, with Niall McCullagh getting Royal Diamond home in front by a head for then-trainer Tommy Carmody.

Murtagh, who was a major of the operation before taking over the licence at his Curragh yard, watched on from Doncaster 12 months ago but will this time be on board and admits it will be even more special if Royal Diamond can strike again.

"He's in good form and came out of the last race very well. I'm very pleased with the way he's progressing since that and hopefully he'll be there to defend his crown," Murtagh told Irishhorse.tv.

"The rain I don't think will do him any harm. He won it last year on good to yielding and I don't think it's going to be soft.

"I think it is (a better race than last year). Everybody is coming into the race in much better shape, it's a much tougher race and there are better horses in it."

Royal Diamond was only confirmed for this race midweek, as connections considered missing the race to instead head to Australia for next month's Caulfield Cup.

A trip Down Under for the Melbourne Cup in early November remains very much on the agenda, however.

"If all goes well he'll be going to Melbourne," Murtagh said.

"He's got two weeks of quarantine before he leaves, he's got two weeks quarantine out there and then he's got nine days before the race.

"He's a horse I think could run very well in the Melbourne Cup. He's good from the gates, he's got tactical speed, which is what you need, and he stays the trip well."