>It's not as is she's not qualified on paper to do this, having once won an All-Ireland singing trophy (I think when she was in a band called Oige...

No Diane, there aren't any All-Ireland singing competitions for bands; she won the All-Ireland at the age of 14 for singing solo, unaccompanied ballads.

>The point of his Woman's Hour promo was, apparently (and scarily) that Ms Dillon is doing a WOMAD workshop on 'How To Sing Oirish'

Again no, Diane, Cara is taking part in a workshop on vocal techniques, for which she is well qualified - her use of ornamentation is good.

From www.digitaldeli.co.uk/news-music-womadsummerschool :

Striking A Chord: A vibrant introduction to the myriad of vocal techniques from Zimbabwe, Cameroon and the British Isles with Coco Mbassi (Cameroon), Cara Dillon (Ireland), Chartwell Dutiro (Zimbabwe) and Kirsty Martin (UK).

Sounds very interesting to me.