" 130 folk clubs" - who counted them ?
By my reconing that puts about 20% of the country's folk clubs within Greater London. But then how are you defining a "folk club"? When does a guest booking club turn into a "concert" and when does a singers club turn into an informal singaround?

I am not sure how you would count folk clubs in a realistic manner. There is no central reguister not every county still has a folk association (Ex EFDSS district) that could provide figures.