Lionel has been in landscape architecture for over 40 years, the last 25 with terra firma and has worked all over the world on all scales and nature of projects, including setting up offices overseas. He is an occasional writer and lecturer on landscape issues and has been involved in the wider profession as an external examiner at the University of Greenwich, Chair of the LI South West Branch and as an LI annual awards juror.

He has been instrumental in reforming the LI International Working Group (something he sat on a decade or so back but was disbanded during a problematic period at the Institute where priorities were elsewhere) and was a founder member of the Humanitarian Group. Lionel is currently an LI Representative to the UK Built Environment Advisory Group: Global Future Cities Project.

He is also keenly involved in community affairs and has been Chair of his local Parish Council, sat on the East Hants, North East Hants and South Downs National Park Design Panels and is currently contributing to an East Hants COP 26 advisory group.