His first big race win came not for Cooper, but for James "Tiny" Edwards on the 1834 Goodwood Cup winner Glencoe I. The following year, his career took another step forward when he won the first of what would become ten Classics, the 1,000 Guineas, on the Charles Greville-owned Preserve. However, it was actually a losing ride on Ascot in the 1935 Derby, going down to Mundig by only a short neck, that "lifted Flatman into the first rank of jockeys". He would later recompense for this narrow miss by taking the St. James's Palace Stakes at Royal Ascot on the same horse. Big race victories would continue into late summer when he took Goodwood's Molecomb Stakes on Elis.