As a "definition", all it defines is your and your club's activities.

No - if defines the nature of Folk Music as it occurs throughout the world; in England certainly. Go to any folk festival, listen to any folk radio show, look through the folk section of your local HMV, and you'll see this to be true.

Actually in my experience, most folk clubs, festivals, radio shows etc stick more or less to my understanding of "folk". Likewise the folk section of my local HMV - I certainly wouldn't look there for George Formby imitators or renditions of "When the Saints go Marching In".

I accepted in my previous post that there are uncertainties around the margins, and certainly I do hear things in all these contexts which strain my understanding of "folk", but that doesn't mean that anything or everything can, or does come, under the umbrella