"Basically we fall out when someone deliberately attacks the hard work we put into what we do."
One of the disturbing aspects of modern research is the it has become a tendency to denigrate the work done by past researchers - Sharp and his colleagues have always been victims, of late, Child has been described as incompetent, even regarding his Poetry research
MacColl and Lloyd... need one say more ?
Unless we learn to incorporate all research into our understand we will end up knowing less than we know now

"I would rather ask Jim and Dick whether our interpretation of song is ok"
The song or the singer? The song every time - the singer should be a conduit between the narrative and the listener
It's the singers job not to get in the way of the song by 'telling it' rather than performing it

The song is THE THING.
"All the time"

"Regardless of the performance"
Depends on how competent it is; a good song (particularly a ballad) can survive an indifferent performance, but if it's bad your audience listens to the faults
In the end, the first person the singer has to move is him/herself

"Or does interpretation matter?"
It's essential - it has to be good enough to communicate to an audience what you FEEL about the song

"As I said we'll go and sing this tomorrow - to a NON folk audience. They will appreciate the craft of the singing and playing."
You can sometimes get over this with a short, clear introduction
The thing to remember is that most audiences want you to succeed - if you convince them you 'have the right to be there' (an old theatre saying), you have won their attention and even maybe their respect

So are we harming the song that we care about performance?
Technical performance and interpretation (reached at by understanding your song) is essential - as long as you pass on how you feel about it - technique and even over-performance can often be a diversion

"When my friend does his listen to Walter Pardon sing - I listen for the song rather than the performance."
Great - that means the song is working and your audience is listening to the song and not you
Walter "saw" his songs, he mentally dressed up his cahracters and placed them in familiar localities
He sang. 'Pretty Ploughboy' once and then pointed out at the field opposite his cottage and said, "He used to plough in that field" (he didn't mean that literally, but's that where he placed the action for the duration of the song.
He one sang his long version of Van Dieman's Land, flopped back in his chair and said, "That's a long old song, but it was a long old journey"
Traveller, Mikeen McCarthy said singing a song was "like sitting in the cinema.
We had similar examples of things like this from many singers
"Is this a purely folk thing or can we talk about blues?"
Blues is the folk music of Black America drawn from their own experiences (as I believe our folk songs are
Broonzy once heard MacColl sing 'Four Loom Weaver" and said "I never knew honkys had blues".
All my opinion, of course
Jim

Repeat I'm afraid, from an interview Pat and I did with MacColl in the 80s

Now you might say that working and training to develop your voice to sing Nine Maidens A-milking Did Go or Lord Randall is calculated to destroy your original joy in singing, at least that’s the argument that’s put to me from time to time, or has been put to me from time to time by singers who should know better.
The better you can do a thing the more you enjoy it. Anybody who’s ever tried to sing and got up in front of an audience and made a bloody mess of it knows that you’re not enjoying it when you’re making a balls of it, but you are enjoying it when it’s working, when all the things you want to happen are happening. And that can happen without training, sure it can, but it’s hit or miss. If you’re training it can happen more, that’s the difference. It can’t happen every time, not with anybody, although your training can stand you in good stead, it’s something to fall back on, a technique, you know. It’s something that will at least make sure that you’re not absolutely diabolical
The objective, really for the singer is to create a situation where when he starts to sing he’s no longer worried about technique, he’s done all that, and he can give the whole of his or her attention to the song itself she can give her or he can give his whole attention to the sheer act of enjoying the song."