Giles is the son of actor Jack Watling and actress Patricia Watling, and the brother of actresses Dilys Watling and Deborah Watling. He also has another sister called Nicola.
He has worked extensively in the British theatre and television, and is probably most well-known for the role of Oswald in Carla Lane's Bread. He married Vanda Brinkworth in 1979 and they had twin daughters (Elizabeth and Jemima) in 1992. He lives by the sea and is a District Councillor in his home town. When both his acting and council commitments allow he is a keen sailor.
Giles appeared with Harry in Hows Your Father playing the part of Harry's son