I seem to have fallen foul of the 'answer once' system. Having not been able to finish answering before I just wanted another look through before I did so, and found I couldn't go back to the start, so merely clicked through to the end - and then couldn't get back in (quite rightly, of course). I also wanted to save some grabs of the pages so that I could - if necessary - cross-reference more easily with Graham at some future date. Anyway, that's one survey submission you have there, Graham, which is not worth the paper it's not written on.
Just two thoughts on a couple of the comments above.
There is no question that taken as a simple expression of common usage (rather than semantic or academic definition), across the UK as a whole, the term 'Folk Club' does apply to a spectrum of gatherings, from the purely participatory (aka singaround club, song session etc.) to what are essentially folk concert venues, where only booked performers play. That is a simple matter of fact.
(It should also always be remembered that the term 'Folk Club' is also typically used to include many gatherings and concerts which follow the traditional (though not necessarily 'Traditional' ;-) 'folk club' format, and/or who book music which is termed 'folk' by some - but which eschew the words 'folk' and/or 'club' in their name).
Not many fold clubs of any description are legally clubs (i.e. with actual membership).
IF I remember correctly, Graham showed cognisance of this on the first page.
What I think did slip through this particular net (not that this is an problem given Graham's presumed objectives) is the tune session. These are almost never called folk clubs, but there is some overlap with mixed sessions and indeed clubs that habitually run tune sessions before during or after the main event - so I for one would have been intrigued to see a survey which included them. But no matter.
David El G's point about 'dwindling' is interesting. From what I can gather, 'consumption' of 'folk' music seems to be on the rise in the UK, but attendance at 'folk clubs' is - nationally - dwindling. So it's legit to ask the question in this survey - (though an additional question to find out what's happening at the specific club being surveyed might have been useful).