Ex-Australian sprinter Starspangledbanner scorched to victory in the Group One Golden Jubilee Stakes on the final day of Royal Ascot Saturday. Now trained by Aidan O'Brien in Ireland and ridden by Johnny Murtagh, the four-year-old made virtually all the running to grab the spoils in a high-class, international 24-strong field. Starspangledbanner is a son of the Australian ace Choisir who blazed a global trail at Ascot in 2003 when winning the Golden Jubilee and the King's Stand Stakes, two famed sprints at the royal meeting. Sent off as a joint favorite, Starspangledbanner was having only his second run for O'Brien since moving from Australia earlier this year. He raced on through the final 200m to win in just outside record time by a length and three-quarters from an outsider Society Rock and American raider Kinsale King. O'Brien, registering his third success at this week's meeting, has been stunned by the colt's improvement since his first race for the stable at York in May when he was fifth. He told BBC television: “His work since York has been incredible. His second-last furlong was just under nine and a half seconds. We've never seen that at home before.” He added: “It is incredible that he was able to win over a mile in Australia and he came over with a massive reputation, we were very lucky to get him. He's the fastest we've had, no doubt. We've never had one go that fast furlong by furlong.” Murtagh said: “He's very similar to his sire Choisir, big and strong. Today when I rode him he was different, he was in a different zone. There was 20 lengths improvement from York.” Murtagh was also on the mark in the next race, another sprint over six furlongs (1.2 km), when he won the Wokingham Handicap on favorite Laddies Poker Two. It was his fourth success of the meeting after drawing a blank on the first three days. The opening Chesham Stakes for two-year-olds went to Zaidan, ridden by Seb Sanders and trained by 75-year