Christopher is a very well-known expert on the ferns of the Indian subcontinent. He has written widely on the taxonomic, cytological and molecular-cladonomic studies of the Indian pteridophytes and recently published the three-volume An Annotated Checklist of Indian Pteridophytes (2021). He has worked closely with other Indian pteridologists and more widely internationally. He has always been a ready source of advice on the identification of ferns, and he is an Honorary Member of the British Pteridological Society and the Honorary Patron of the Exotic Fern Group. Born in South Wales, he currently lives between Portugal and the UK, having moved from Nepal.