New Doctor Who Spin-Off?

For the continuity nuts: The BBC are developing a new series for the Who slot on Saturday nights based on the legends of Merlin who as we all know from sitting through the Sylvester McCoy adventure 'Battlefield' is a future incarnation of The Doctor.

"He regenerates at least once (Ancelyn knows of this ability) and helps Arthur win many battles (including Camlann). Finally, around the year 1200 at Badon, the Doctor defeats Morgaine's armies completely. Arthur is killed in the battle, and the Doctor, pretending that he's putting him in suspended animation, sends his body across the dimensions to the 'Avalon' lake in our universe (The propaganda value of the idea that the King might awaken when cured, and use Excalibur to call for aid, would help in restoring order)."

Casting ideas?