Well, hard to say really, he was Head of Natural History for North Herts. Countryside Officer for same area. General Natural History and Conversation is his expertise I suppose. He is knowledgeable in Botany, Ornithology, Geology, British Mammals, Butterflies and has written on Butterflies of Hertfordshire and Wild Flowers of Hertfordshire and their Habitats. Bit of a know- all really 
kidding he is a very modest man who share his knowledge readily giving talks and running courses. He is also a pretty good photographer (wildlife and landscape of course)
When he was sedated for 3 weeks in hospital 2 years ago, I walked into his room one day to hear a nurse say to another 'I told you it was BS the Black Squirrel man off the TV'. She apologised saying that she was dying to tell someone but couldn't tell her family so dragged another nurse into the room.
