HORSE racing lost one of its greatest champions in action yesterday when triple Gold Cup winner Best Mate suffered a suspected heart attack on his return to action at Exeter. Trainer Henrietta Knight was first on the scene after jockey Paul Carberry - riding the ten-year-old for the first time - dismounted after the fourth-last fence of the William Hill Haldon Gold Cup when it became clear the horse was struggling. Screens were quickly erected around the stricken Best Mate, but vets were unable to save the gelding, who amassed more than £1 million in prize-money, having won 14 and...