Here’s an article that paints Sir Francis Dashwood (1708-1781), founder of the infamous Hellfire Club as a proto-pagan.
Disinformation has a short summary and a good list of links on the subject. It also mentions the Irish hellfire club, which predates Dashwood’s society.
One point made is that “hell-fire club” is not what Dashwood and co. called themselves; it was probably a general term for social clubs for rowdy and hedonistic young aristocrats (“rakes”).