[2] He was trained by Barry Hills in Lambourn and owned by friends Steve Falle, Matt Franklin and James Sumsion.
As a three-year-old, Prime Defender won the European Free Handicap at Newmarket Racecourse in April and the Sandy Lane Stakes at Haydock Park in May.
He recorded his most important victory as a six-year-old in August 2010 when he won the Group Two (Duke of York Stakes).
Prime Defender was retired to Hedgeholme Stud in County Durham at the end of the 2011,[4] but after having fertility problems he was returned to training the following year with the Nottinghamshire trainer Michael Appleby.
He was being prepared for a return to racing when he died of a heart attack in a training gallop on 24 July 2012.