Straight after the final episode of Doctor Who the BBC ran a (very) short trailer which basically consisted of the following screen.
A look on the BBC wesbite reveals nothing at the time of writing.
So I did a quick Google search and found this article on the Guardian from 2005.
Merlin is one of a number of dramas being developed for the 7pm Saturday slot following the runaway success of Doctor Who earlier this year, which is credited with reviving family viewing.
The new BBC1 drama would concentrate on Merlin’s early life. In literature and on screen Merlin has been variously portrayed as a key figure in the Camelot story, acting as King Arthur’s adviser, poet and magician, but also as a villainous character.
There is also a later article from the Guardian from this year which has more detail, notably that Anthony Head is in the series.
The BBC has started filming on Merlin, a fantasy drama about Arthurian legend featuring Buffy the Vampire Slayer and Little Britain star Anthony Head and One Foot in the Grave’s Richard Wilson.
The 13-part drama will be broadcast in the autumn and stars a trio of newcomers as the young Merlin, Arthur and Guinevere.
Head will star as Arthur’s father, Uther Pendragon, while Wilson will play court physician Gaius in the Saturday teatime BBC1 series, slated for the family drama slot occupied by the likes of Doctor Who and Robin Hood.
The drama will be set in the mythical city of Camelot, and focus on Merlin as a wizard on the brink of adulthood who clashes with a young Prince Arthur.
Looks interesting. Sounds similar in style to the BBC’s Robin Hood.