He was sired by Cyllene, an Ascot Gold Cup winner, who went on to become a highly successful stallion.
Polymelus's dam Maid Marian was a half-sister to the outstanding racemare La Fleche and later became an influential broodmare in her own right, being the foundation mare of Thoroughbred family 3-f.
Her other descendants have included Big Red Mike, Mioland, Mont Tremblant, Pont l'Eveque, Right Royal and Saint Estephe.
As a three-year-old in 1905 he showed form over a wide variety of distances, winning the Duke of York Stakes over six furlong and finishing second in the St Leger.
[3] In 1906 Polymelus was offered for sale at Newmarket and bought for 4,200 Guineas by Solomon Joel.