Darby has a PhD in organic chemistry (natural product total synthesis) from the University of Canterbury, New Zealand. He worked for ten years in drug development at the Auckland Cancer Society Research Centre, University of Auckland, followed by five years at Cawthron Institute, Nelson, working in various areas of analytical chemistry and microscale synthetic modification of natural products. He has also worked as a freelance academic editor and at a large commercial plant nursery.

Outside of work, Darby enjoys keeping fit and flexible, reading widely, listening to music, making jams and jellies, coffee, gardening, quizzes, and keeping up with his family.