Mill Reef, the American-bred winner of the...

Mill Reef, the American-bred winner of the 1971 English Derby horse race, died Sunday at the age of 18 after suffering from a serious heart condition.

Mill Reef, owned and bred by Paul Mellon, was trained at Newmarket, England, by Ian Balding. Mill Reef, ridden by Briton Geoff Lewis, won many of Europe’s top races including the Prix de l’Arc de Triomphe at Longchamp, the Eclipse Stakes at Sandown and the King George VI and Queen Elizabeth Diamond Stakes at Ascot.

He retired to stud in 1973 and sired 1978 English Derby winner Shirley Heights.