Complex sentence: Flockton Grey was the British racehorse at the centre of one of the largest betting scandals to hit British horseracing, which remains the best-known case of a corrupt trainer and owner using a ringer to race in place of another horse.
Split into simpler sentences: Flockton Grey was the British racehorse at the centre of one of the largest betting scandals to hit British horseracing. The affair remains the best-known case of a corrupt trainer and owner using a ringer to race in place of another horse.