Mrs. John Magner's Ad Valorem, a 2-year-old son of Danzig--Classy Woman (by Relaunch) gave trainer Aidan O'Brien his group I victory of the British racing season with an impressive victory in the Shadwell Stud Middle Park Stakes (Eng-I) at England's Newmarket racecourse.Ridden by Jamie Spencer, Ad Valorem was well-placed near the front as Prince Charming set the early pace. Ad Valorem was set down for the victory a furlong from the finish and held off a fast-closing Rebuttal, a U. S.-bred son of Mr. Greeley for a three-quarter length triumph. The final time for six furlongs was 1:12.19 as favored Iceman finished third.Bred in Kentucky by Calumet Farm, Ad Valorem was purchased by Thomas Magnier for $450,000 from his breeder's consignment to the 2003 Fasig-Tipton Saratoga selected yearling sale.With the victory, Ad Valorem remained undefeated in three career starts and was installed as one of the favorite for next year's classic Two Thousand Guineas (Eng-I)."It didn't look like he was stopping and was holding on strongly," O'Brien told Racing Post. "Jamie thinks he will stay further than six, but the colt has a lot of natural speed too."