I think I must be the only person who counts this as one of their favorite episodes. I love stories about crazy cult leaders; I'm always interested in what motivates them, and why people choose to follow them. I'd love to see an origin story for Dr. Sevrin - how he became mentally unbalanced, and how he became ill.
He used to call himself Julian Clegg and was the presenter on Most Haunted's live specials a few years back!

JB