 In 1979, she was visiting scientist on an American expedition (by sailing ship) to an uninhabited island in the Bahamas, and she took parties to Jamaica, New England, and the Rocky Mountains.Other expeditions were to North, West, East, and Central Africa, and Florida, and she led groups to various parts of Britain and Europe.Active in various natural history and conservation bodies over several decades, Gillham was president of the Glamorgan Naturalists' Trust and of the Cardiff Naturalists Society.