First of all thanks for reminding me of how good the 'In Our Times' series was.

Steve Gardham asks;

"Just a thought, what evidence have you that any of this is 'folklore' as opposed to literature of the elite?"

As soon as Thomas of Britain wrote it down it became 'literature of the elite'. Before that it appears to be not known to the elite and therefor possibly 'folklore'. Thomas talks about different versions with different plots. He compiles different bits into his own single version. This gets picked up and translated into other languages. We know this because the written records survive. In earlier cultures, particularly Celtic and Norse, records were memorised and not written (other than by clergy). So there cannot be 'evidence' of it being folklore other than it's actual existence and possibly what Thomas or others write about it.

I find the question itself rather disturbing.

Is it saying 'Elite literature bad, folklore good'? Are we, the folk, not allowed to engage with it because it has been polluted by it's elite provenance? Is this a kind of folk iconoclasm?