Complex sentence: The Diadem Stakes is a Group 2 flat horse race in the United Kingdom for three-year-old and above thoroughbreds run over a distance of 6 furlongs (1,207 metres) at Ascot Racecourse in late September.
Split into simpler sentences: The Diadem Stakes is a Group 2 flat horse race in the United Kingdom for three-year-old and above thoroughbreds. It is run over a distance of 6 furlongs (1,207 metres) at Ascot Racecourse in late September.