On 3 April, the colt was moved up in class for the Group Three Prix de Barbeville over 3100 metres at Longchamp Racecourse in which he was opposed by the double Ascot Gold Cup winner Sagaro.
[4] In June, Buckskin was sent to England and started favourite for the Ascot Gold Cup, but was beaten five lengths by Sagaro who was being ridden for the first time that year by Lester Piggott,[5] leading to speculation that he needed soft ground to produce his best form.
He was less successful when brought back to shorter distances, finishing unplaced in the Prix Kergorlay at Deauville Racecourse in August, having twisted a plate in the race and then running third in Preis von Europa over 2400 metres in Germany.
Walwyn found that the horse had foot problems which made him difficult to train and on his debut for his new handler, Buckskin was disappointing, being well-beaten by Shangamuzo in the inaugural running of the Sagaro Stakes at Ascot in April.
At Ascot in June he started 11/8 favourite for the Gold Cup, with his main opposition expected to come from Shangamuzo and the Park Hill Stakes winner Royal Hive.
[8] Buckskin's training problems worsened, as his flat feet and weak suspensory ligaments made him an extremely fragile horse[9] and in all his subsequent races he appeared with heavily bandaged forelegs.
Ridden by Joe Mercer and starting at odds of 5/2 he took the lead in the straight and drew away from his opponents to win by eight lengths, with Billion taking second ahead of Shangamuzo and Sea Pigeon.
Ridden by Mercer, and starting at odds of 10/11 he drew away from the field in the straight and won by fifteen lengths[9] from Pragmatic (winner of the Yorkshire Cup) and Arapahos.
Mercer opted to ride the horse in preference to the stable's other runner Le Moss, a four-year-old who had finished second in the St Leger and was partnered by Lester Piggott.
Looking somewhat uncomfortable on the firmer ground, Buckskin took the lead half a mile from the finish but was unable to establish a decisive advantage and was challenged in the straight by Le Moss.
In the inaugural International Classification, he was rated the equal of Sagaro as the sixth-best horse of any age in Europe, behind Alleged, Blushing Groom, The Minstrel, Balmerino and Orange Bay.
[11] Buckskin was retired from racing after his defeat in the 1979 Gold Cup and began his career as a breeding stallion in 1980 at the Fawley Stud near Wantage in Oxfordshire at a fee of £1,500.