David practised in many fields of veterinary science between 1965 and 1975 in New Zealand, United Kingdom and Australia and was a consultant veterinarian to Manly Ocean World between 1989 and 2000.

David directed the design, construction, stocking and operation of the Western Plains Zoo for Zoological Parks Board of NSW 1976 to 1984.

David did a study tour of major zoos in North America in 1979 and was then appointed assistant director of the Zoolological Parks Board of NSW and in 1981 assistant director of Taronga Zoo from 1984 until 1986.

During 1987 David was appointed deputy director of the NSW RSPCA. and then director .

David went into private veterinary practice with a partner at Bankstown Veterinary Hospital in 1993 and is still there.

And so it goes on, David is the project manager of Foundation for Agricultural Conservation Technology and Science 1993, member of the animal research review panel, chief executive officer World Wide Fund for Nature Australia and chief executive officer Greening Australia NSW at present.

David has major interests in natural history, the environment and its conservation, natural resource management especially innovative methods of water and land management.