Complex sentence: He was Chairman of the National Advisory Council on Art Education between 1958 and 1971, which published its first report in 1961-called the "Coldstream Report"-outlining the requirements for a new Diploma in Art and Design (Dip.A.D.).
Split into simpler sentences: He was Chairman of the National Advisory Council on Art Education between 1958 and 1971. The 1961 report of the Council-called the "First Coldstream Report"-outlined the requirements for new Diploma in Art and Design (Dip.A.D.).