Van Geersdaele studied at Hammersmith Technical College from 1946 to 1949, after which he engaged in moulding and casting at the Victoria and Albert Museum until 1951. From 1954 to around 1976 he was a conservator at the British Museum, rising to the position of senior conservation officer in the British and Medieval department. Following that he became an assistant chief of archaeology in the conservation division of the National Historic Sites of Canada for Parks Canada, and then the deputy head of the conservation department at the National Maritime Museum in London.