He's a very, very well known guinea pig person. He bred pigs and went to shows, and wrote quite a few popular piggy books. He also took his pigs to Great Ormond Street Hospital (children's) for visits and built up a big reputation as a "guinea pig guru". Much of what he said was outdated and old-fashioned but was and is still trusted by many (few here though, as we have up-to-date information which is with the times and new details, more recent views and research etc.).
The guestbook on one of his websites states the death, by - I believe - someone who knew him personally.