"Show me where I can share the provenance of a Child ballad, note the historical context of the circumstances that the song arose from and get genuine interest for hearing how and why I apply a particular musical style, that cadences were evolving at the time due to the influence of Bach in church music, allowing a freedom of expression in ballad tunes...." "If you want lots if people to listen earnestly whilst a retired teacher from Harpenden gives a ten minute lecture on highland crofting before sticking his finger in his ear and clearing the room, good luck." Why are these two (similar) examples in separate paragraphs?
Is either quoted as an example of a "Folk club"? If so in what way do they reflect the process by which songs originally found their way into what became known as the folk repertoire? Is this what the Coppers were doing all the time, or Sam Larner?
"If you want pub acoustic nights to stop calling themselves folk, good luck." Are you suggesting that the gatherings of 20+ singers down the pub every couple of weeks singing choruses, Child ballads and songs Baring-Gould tried to rewrite should not be considered "folk": nor the monthly session in the bar playing mainly Irish tunes, or the monthly music session led by third generation (at least) instrumentalists playing local English tunes? (OK – perhaps those aren't the acoustic nights you meant.)
True, I'd happily go to the "Child ballad" venue myself whereas I won't go near anything that says "open mic" but I'd not like to claim one was folk and the other wasn't.
Back to the OP – when songs are written they're not folk songs, they're just songs. If they get processed they may evolve into folk songs. So you can have a new folk song but it will already be an old song and it's impossible to detect a precise point at which it became "folk". The thing with evolution is that you usually can't detect it until after it's happened and there's no precise point during the process that you can identify as the only point – you can't predict during the process what it's becoming (you can just identify variation), you can only tell after the process what it has become.