Ruler Of The World triumphs in Epsom Derby By Justin Palmer EPSOM, England (Reuters) - Late developer Ruler Of The World belied his racecourse inexperience and lived up to his name and impeccable breeding to land a fourth English Derby for Irish trainer Aidan O'Brien at Epsom on Saturday. The 7-1 chance, the latest Classic winner to emerge from O'Brien's Ballydoyle stable with a bloodline to the cream of the sport, proved too strong for 11 rivals under jockey Ryan Moore. Unraced as a two-year-old and having only his third run, the unbeaten colt had 1-1/2 lengths in hand at the line over Libertarian (14-1), with Galileo Rock (25-1) third in the 234th running of the famous race. The major disappointment was hot favorite Dawn Approach (5-4) who came home last. Ruler Of The World is the son of Galileo who provided the County Tipperary-based O'Brien with his first Derby victory in 2001. He also won the blue riband of British flat racing with High Chaparral in 2002 and Camelot last year. Every season O'Brien has the offspring of flat racing's top stallions at his disposal thanks to the Coolmore breeding empire and the deep pockets of his backers, owners John Magnier, Michael Tabor and Derrick Smith. We are so lucky to be in the position we are in. To get such horses," O'Brien, who saddled five in the race, told reporters. They are incredibly bred horses and, even before they are mated, the dream is for this to happen. Ruler Of The World, he said, had earned his name from his early days at Ballydoyle. "I was afraid to run him as a two-year-old with a name like that," he joked. He has an unbelievable pedigree. But he earned his name from an early age - it speaks for itself. It was not quite another double O'Brien triumph. The trainer's son Joseph had high hopes of a second straight Derby success after Camelot but opted, with his father's blessing, to ride Battle of Marengo, who finished fourth. "Joseph had his choice and I would say Aidan thought this horse (Ruler Of The World) was next best," said Magnier, whose father-in-law Vincent O'Brien won six Derby races as a trainer between 1962 and 1982. This year it has been more difficult than ever because they didn't know where they were with the horses. It's been the same for everybody - the weather has been so difficult. It was Moore's second Derby triumph following victory on Workforce for Michael Stoute in 2010. "He's still a baby," said Moore, adding without a hint of irony that "if he continues to progress he could make up into quite a nice horse. I was there too early but he really toughed it out and showed a good attitude. Running in Dubai ruler Sheikh Mohammed's Godolphin colours, Dawn Approach never settled and confirmed worries the English 2,000 Guineas winner lacked the stamina for the 1-1/2 mile race. "There wasn't much pace early on and the horse grabbed the bridle," said trainer Jim Bolger, who won the Derby in 2008 with New Approach. From then on, he was more or less out of control. A victory for Libertarian, 100 years after suffragette Emily Davison sustained fatal injuries after running on to the Epsom track and bringing down King George V's horse Anmer in the 1913 Derby, might have been apt for female trainer Elaine Burke. No woman has trained the winner of the Derby and Yorkshire-based Burke was the seventh to have a runner in the race. Reporting by Justin Palmer, editing by Ken Ferris