Madeleine Pickthorne was employed as a temporary Dutch elm disease officer by Somerset County Architect's Department from January 1973 to September 1974. During this time, she became involved in the restoration of the Formal Gardens at Hestercombe House, near Taunton, and was responsible for drawing up plans for the recreation of the Gertrude Jekyll planting for the Grey Walk, the East and West Rill Terraces and the Great Plat.
Madeleine subsequently worked as a landscape designer for Devon County Council from 1974 to 2005. She designed school grounds (including Cowick First School, featured by Learning Through Landscapes in their video, Grounds for Celebration) and highway planting schemes such as Hatherleigh by-pass. She also project-managed the creation of Devon's Garden at La Colline aux Oiseaux in Caen, Normandy, France for the 1994 commemoration of the D-Day Landings.
Ms Pickthorne was a founder member of the Devon Gardens Trust and initiated their Devon tree register.