Following initial training as a fine artist Stuart went on to study geography at Newcastle University. Stuart joined the Scottish Wildlife Trust in 1995 supporting a European peatland project eventually leaving the Trust in 2009 as their Director of Conservation.
He joined the John Muir Trust, a UK charity concerned with protection of wild places, as its Chief Executive in 2009. He joined the National Trust for Scotland as its Head of Natural Heritage in 2017.
Stuart is currently the Chairman of the International Union for Conservation of Nature (IUCN) United Kingdom National Committee.