By 'doggerel' I meant and said that it's not an ego trip in which you show how many syllables you can get into a line or how cleverly you can craft a rhyme. The extract from 'Beowulf' above is just that. (Possibly why nobody sings it? :-)) The writing of a song is always conscious 'art' but in the case of traditional song it doesn't spund like it. What comes over to us as listeners to traditional song is the very 'artlessness' of their construction, even the most beautiful. The use of grammatically incorrect syntax and archaic or 'odd' words also have their place too. When listening to traveller singers I am often struck by the way they forget or misremember a line and just sing what happens in the story despite there being, to my ear at any rate, an obvious rhyme which they could use to maintain the rhythm and structure. Yet they don't do it.
On the same point, and he can correct me if I'm wrong here, I'll bet John Connolly never looks out of the window at 5.00pm and remarks, 'what a rare evening'. Even if he is intending to go for a 'walk by the dockside'. Despite this, 'Fiddler's Green' is about as 'traditional' as you can get.