Giles started sailing Optimist dinghies in 1994 on Grafham Water in Cambridgeshire. It took about a year before he became interested in racing. In 2001, at the age 14, Giles got his first taste of being the best when he became the youngest ever Topper National Champion. In 2005, he came away with gold at the ISAF Youth World Championships.

After this success, Giles made the transition into Senior Laser racing, achieving seventh place at the Senior Laser worlds where he was the first under 21 to compete. In 2006 Giles decided he was better suited to the Finn Class. Within ten months, Giles finished fourteenth at the ISAF World Sailing Games. He went on to win the UK Finn National Championships in 2007.