Jim C,
I have no wish to argue with you. I admire the work that you do, I have never met you but going back decades I used to work with you and Pat in booking the traditional singers that I was arranging tours for into the Singers' Club. I would agree by and large with your definition of folk song.
However - and I am really not trying to be rude or accusative here - I find that there are elements in your statements that are inconsistent and somehow stuck in a time warp and not aware of the rapid changes that have taken place in the music scene in England, both in folk clubs and in the broader scene.

Let me just make a point here as an illustration of what I mean.
You wrote:-
If I want Jazz - one of my other interests, - I seek out a a jazz venue, somewhere advertising jazz - If I don't find it there, I don't go back.
Well, there is something else we share; a love of jazz. I went to a concert at the London South Bank complex in November 2014 as part of the London Jazz Festival. It was given by Kassé Mady Diabaté, Makan Tounkara, Lansiné Kouyaté & Ballaké Sissoko. This concert by four Malians was by some distance the best performance that I attended that year and I go to many concerts, festivals and clubs and hear a lot of live music. The other big sell-out concert at the festival was one of the leading Cuban 'Son' performers; again excellent - but not jazz. Looking through the programme the majority of the events were what I (and I suspect you as well) would call Cocktail Jazz or Jazz Funk. Why is this? Well, the audiences for what you and I would regard as jazz has collapsed and the experimental modernists have left their audiences behind. If you wanted to go to hear a beefy sax player leading a small group playing be-bop or mainstream jazz in a small or medium sized venue in the days when you lived in London you would have been spoiled for choice. Not so today.
It would be futile to try to point this out to the festival organisers. They need to make ends meet financially and still put on a modicum of the music that they love. I am pretty sure that without strong Arts Council Support and BBC Radio 3 broadcasting a high proportion of their events that the festival would not be there at all.

I have taken the example from outside folk music in the hope that it will be less contentious but the same thinking exists with folk music promoters. Barriers between genres are breaking down, the whole wide availability that the information revolution has brought about has contributed to making people looser in their thinking about music. There are many crossovers. Young people do not seek out folk clubs to hear folk music. One of the greatest singers of traditional ballads of his generation is Alasdair Roberts, a professional and and outstanding performer. We booked him several times at our folk club but very few others do and nearly all his gigs are in mainstream venues.
You praise great friends of mine, Ken Hall and Peta Webb for their work at Whitby Festival and I have been fortunate enough to have been booked in take part in these. They also run the superb Musical Traditions club in London and there is an article by me on 25 years of their club in the current issue of English Dance & Song.
Their club is one of the most dedicated to traditional song in the country. Let's ask some questions about this lovely pair and the club they run:-

Is their repertoire exclusively traditional?
Well, no, when they sing together they sing a lot of songs that derive from the 'brothers' duos of early country music. Ken favours singing comic songs, many by the late, lamented ex-mudcatter Fred McCormick

Do they only have floor singers who perform traditional songs?
Well, no. One of their regulars is an Irishman who I would describe as a performance poet. Two other regulars draw their repertoire from the London Music Hall.

Is their booking policy to book exclusively traditional singers or those who sing traditional songs?
Well, no. In December their guest was that great singer/songwriter Pete Morton and their regular guests include top English eccentrics like Jim Eldon and Tony Hall whose repertoire we might call 'eclectic'. They even book (and whisper it gently) Jim Bainbridge.

Are there evenings at their club and at their Keith Summers Memorial weekends when a minority of songs will be traditional?
Yes.

I reckon that in all my years of organising folk clubs the vast majority of the guests that I booked were either traditional singers or those who loved the tradition, but it would be no good me sitting on my throne at low-tide shouting at the incoming tide. "Go back! Don't are come into my folk club with your watery non-traditional songs!" because very soon my feet would be wet and I would be drowned.
All I can do, as I have tried to do all through my life as performer and organiser is to promote good performances of traditional song and music and then let the material weave its own magic charms.