I'm on a mailing list with Scots songs and music on it, and 'folk' still seems to have some meaning there. On the other hand the subject of 'Jacobite' songs turned up, and those could be just about anyting along those lines from 1684 when Catholic James I came in, to 1998, on either side, but usually favouring the rebels. They haven't really defined the term.

The advantage of the 50 years is that folk wisdom also has time to separate the wheat from the chaff. Traditional songs aren't senseless ditties, unless they were made to be humorously nonsensical. They should have long outlasted the original singer, so we know its the song that's good not the author/singer. I'll repeat here what Art Thieme added to a prior note, and I gave in an earlier thread, a bit of folk wisdom from an uncle: The song isn't good because its old, its old because its good.