 He is a self-employed private, independent, zoological researcher, consultant, natural history author, photographer and publisher.Clifford's early ornithological positions included the Taronga Park Zoological Gardens, Sydney, The Natural History Museum, London, and the Royal Society of London Research Station, Albabra Atoll, Indian Ocean where he met his future wife Dawn Whyatt Frith.Their full-time partnership began in April 1973.