For what it's worth my observations across the land suggest a significant decline in pub trade mainly due to the smoking ban - with the beer prices against supermarket loss-leaders a close second. Many -most? - pubs were ghost towns through the winter, and perhaps double figures of folk clubs are in trouble as a result.
Warmer weather may grant a few months reprieve, as smokers are happy to sit outside, but many people have now broken the habit of pub-going and may never re-acquire it.
The ban doesn't affect club attendance directly, but it affects pub atmosphere and therefore club atmosphere. I know of many pubs who are now only opening at weekends, with major consequences for some folk clubs.