Order Of St George ran out a facile winner of the Palmerstown House Estate Irish St Leger providing his trainer Aidan O'Brien with a Group 1 treble and his jockey Joseph O'Brien with a Group 1 double.

An impressive winner of the St Leger Trial over the course and distance on his last start the son of Galileo was available at 11/4 last night, opening on-course at just 6/4 before going off the clear 5/4 favourite.

Settled towards rear he made progress through the field with over four furlongs to race.

He came through to lead with two and a half furlongs to go and he stretched clear when ridden over a furlong out, going on to score by eleven lengths. Agent Murphy took second under Jimmy Fortune for Brian Meehan at 6/1 while Wicklow Brave was a neck back in third under Paul Townend for Willie Mullins at 20/1. Forgotten Rules who was sent off the 9/2 second favourite, finished fifth while last year's winner Brown Panther pulled up quickly with under seven furlongs to race.

It was later revealed that he suffered a fatal injury and was put down.

Aidan O'Brien, whose treble came in at just over 35/1, said afterwards: "He was very impressive here the last day.

"I didn't say anything to Joseph but they went hard up front and he put him asleep. He sneaked through lovely and is a very good stayer.

"He got the trip really well and travelled very strongly. When Joseph said go he quickened up very well.

"It's unusual for a horse that stays that well to have that kind of class. He's a very exciting horse.

"We may have a look at the two-mile race at Ascot (the Qipco British Champions Long Distance Cup next month) with him.

"He's a free sweater and if he didn't do that you'd be worried."

Joseph O'Brien, who was recording his first win in the Irish St Leger, added: "He is a very good horse. He travelled exceptionally well.

"I probably got to the front a furlong and a half too soon but I was going so well I didn't want to wait too much longer. In hindsight I probably should have but he has a huge engine.

"It just got a little bit on the bend but I was going easy and he handles a bit of juice in the ground."

Paddy Power go 5/1 (from 8's) about the winner for next year's Ascot Gold Cup.

Additional reporting by Gary Carson