Somebody earlier asked about songs written since my birthday (1954) are considered traditional nowadays...
Well, virtually everything written by Cyril Tawney for start. Various songs from the writings of John Tams, Brian Peters, Pete Morton, Bill Caddick, Peter Bond, and myriad others. Many of which I have heard performed by other people (and very nicely) All of the performers thought that they were traditional, having learnt them 3rd or 4th hand from other singers. Or in a singaround. That sort of blurs the boundaries anyway. It's even more blurry when it comes to tunes.
A lot of tunes played in sessions and known and loved by many, appeared in the last 10 years!
It's always nice to know the name of the writer of a song or the provenance of a tune. I really enjoy threads about such subjects both here and other places.
But it doesn't prevent my enjoyment of a great performance even if the performer hasn't a clue as to where it came from.