Complex sentence: The most significant figure in the development of architecture in Scotland from the 1980s was the academic Charles McKean, secretary and treasurer of the Royal Incorporation of Architects in Scotland (RIAS) from 1979 to 1995.
Split into simpler sentences: The most significant figure in the development of architecture in Scotland from the 1980s was the academic Charles McKean. He was secretary and treasurer of the Royal Incorporation of Architects in Scotland (RIAS) from 1979 to 1995.