Career
He is best known as a co-author of the highly acclaimed Collins Bird Guide, with Killian Mullarney, Lars Svensson and Peter J. Grant. He has designed several series of Swedish stamps. He has contributed to the following titles:
Collins Bird Guide, with Killian Mullarney, Lars Svensson and Peter Grant
Handbook of Bird Identification, Mark Beaman and Steve Madge
Country Life Guides, Birds of Britain and Europe, Håkan Delin et al.
Handbook of the Birds of Europe The Middle East and North Africa (Birds of the Western Palearctic), South. Cramp et al.
