There is the modern concept of legal copyright and recording credit which has altered some of the definition of traditional. Many folk songs may be thought of as traditional and even handed down a few generations, but are modern copyright. I found a song my father wrote written in Inverness Scotland in 1963 on the Irish Traditional Music Archive taped session collection being wrongly thought of as trad. when I am the same darned age as the song. In the UK Modern copyright is 70 years after the death of the author/composer, then it can be called traditional. It's like Flower of Scotland or Fields of Athenry etc.. everyone virally knows them down a few generations, but not every member of the public today has now heard the original recorded versions, knows who wrote them, or have seen the sheet music.