After attending
Abingdon School from 1971 to 1976, Walker studied for a BA degree in
Botany at
University College,
Oxford, from 1977 to 1980. He also holds a lectureship in
Plant Conservation at
Somerville College, Oxford, and is a lecturer in biology at the
Department of Biology, University of Oxford. He has won four
gold medals at the
Chelsea Flower Show in
London. In June 2011, Walker presented
Botany: A Blooming History, a series of three television programmes broadcast on
BBC Four, covering the
history of botany. The series was repeated, again on BBC4, in August 2022. ==Publications==