"Apparently when one sings in folk clubs (and I'm on the other side of the pond, so about all I "know" about British folk clubs is the impression I get reading the threads here on Mudcat), one must be very careful to know ahead of time what predispositions and prejudices that specific club has before one risks opening one's mouth, lest one be smote hip and thigh and cast hence. "

Don, I don't think it's quite that bad, although there are a few clubs where that might apply. What is true is that the range and type of music can vary widely between different clubs, and you may find that what is played in any particular club may not be to your taste, and what you want to play to them may not be to their's. It's usually possible to find a club which suits you (although it's becoming harder as the number of clubs seems to diminish) but as a one-off visitor you may take a bit of a chance on whether or not it's your kind of club. Fortunately most clubs now have websites so it's possible to get an idea beforehand.