It's that Welsh fella.
I was watching Merlin Series 1 ep 8, "The Beginning of the End" where Merlin and co. first meet Mordred ... and that man who plays the druid Cerdan (Mordred is his apprentice) looked so familiar ... and I realized ... he plays Mo in The Hungry Earth/Cold Blood. (Yeah, those episodes). Watching Merlin is like playing 'spot-the-actor-from-Doctor-Who'.