Lyon Playfair was a multi-talented man: a scientist, administrator and politician whose life and influence deserve further research. This article concentrates on the period between 1818 and 1858, from Playfair’s birth to his appointment as Professor of Chemistry at the University of Edinburgh. His biographer (Sir Thomas Wemyss Reid) described his life as a ‘story not of adventure, but work’ and yet his record was one of energetic enterprise that had considerable impact. He was a rising star in the then fashionable world of chemistry, a favoured student of the founder of organic chemistry, Justus Liebig, and a central figure in the promotion of new ideas in agricultural science. A career in science and the state saw him connected to the leading figures of both, and he played a crucial role in the conceptual and financial success of the Great Exhibition, and its legacy. His brilliance has been overshadowed by the extrovert Henry Cole, and yet Playfair was essential to the major educational reforms of their time.