By Sir Gaylord, out of Attica, Sir Ivor (1965-1995) was owned by the U.S. Ambassador to Ireland, Raymond R. Guest. The horse was named for his grandfather, Sir Ivor Guest, 1st Baron Wimborne. Ridden by Lester Piggott, Sir Ivor won many important races as a two-year-old, and the following year earned Horse of the Year honors for his wins in the English 2,000 Guineas, the Epsom Derby and the Washington D.C. International. At stud, at Claiborne Farm in Paris, Kentucky, he sired 94 stakes winners and was the broodmare sire of more than 145 stakes winners.