User blog comment:OneofthePendragon94/The age of Merlin, Arthur, Morgana and Gwen./@comment-3012002-20121115010308

Well John Hurt's narration from Series 1-3 said 'young boy' meaning that Merlin was at least 18 when he arrived in Camelot and he was about 21 in Series 4 which was why the narration for both Series 4 and 5 says 'young man'. Since Arthur came of age during the last part of Series 1 then he's 3 years older then Merlin. As for Morgana and Gwen that's a little difficult to determine.

Um... Uther said in the first episode of Series 1 that Morgana wasn't around during the great Purge but when it was revealed that Morgana was Uther's daughter, it made me think that she might have been older then Arthur by only a few months or younger if you think back to what Uther said. I know the show is only loosely based on the legend but remember, Morgan(a) is a lot older then Arthur in the legend as she and her sisters were born before Arthur.

Gwen I have to say is around the same age as Merlin as Elyan is a bit only then her by only a year or so possibly. I'm only going on my gut. Remember also, Arthur would have to be older then because in medieval times, women married then who were a lot older then them. But I don't think there's a bit gap between them as they would have grown up together as Gwen was Morgana's maid since Morgana was ten years old.