Cley: Prion, (2004. third edition). Octavo, paperback, black and white photographs, other illustrations.

All of the sites described in the second edition, along with a host of new ones, have been visited, verified and been given revised or new text. The bar graphs of seasonal distribution and the section on selected species of birds has been updated. Entirely new in this edition are a brief summary of the islands' biota, complete lists of mammals and of amphibians and reptiles. Combined with thorough travel advice and information on local contacts and societies, this exceptionally well organised and rigorous guide is more useful than ever.