“And in the battle of Arfderydd my torc was of gold…” From ‘Yr Afallennau’ (‘The Apples’), a poem in the Black Book of Carmarthen I don’t know about you, but when somebody mentions the name ‘Merlin’, an image of a bearded sorcerer pops straight into my mind, quickly followed by King Arthur and several valiant Knights of the Round Table.   Add a couple of fire-breathing dragons, a gleaming but inaccessible sword, and a darkly beautiful villainess, and by this time I’m probably thinking about re-watching the excellent TV series starring Colin Morgan in the title role. I have always been interested in the theories about the origins of Merlin, the…