User blog comment:GianG/Merlin characters ages/@comment-5674726-20141116000448/@comment-5674726-20141116200223

You also have to consider the context of Gwen's comment.

She and Gaius were talking about Uther's condition following Morgana's betrayal so the relevant period is the time since he knew of her betrayal, as it would obviously have had no effect on him before he knew of it. It would be ridiculous for her to say "a year" if it was really eight months plus four months that Morgana was working with Morgause unbeknownst to Uther.

Regardless of what was said in the interview, it is not canon. Gwen's comment is