After a long and successful career as a commercial artist working in Fleet Street, Gillingham retired to St Ives in the 1940s. Although quite elderly, he continued to work daily in his studio that was near his Porthmeor residence.

Shortly before his death in his eighties, he contributed some illustrations to a children's annual, More Adventures of Buffalo Bill. He painted principally in watercolours and was fond of depicting French crabbers in the harbour.