Ancelyn

Ancelyn ap Gwalchmai (anglicised: Ancelyn, son of Gawain) was Knight Commander of the Britons under King Arthur in a parallel world in which Arthur actually existed. His name suggests that he was of Welsh extraction. Ancelyn was a noble and honourable knight: though he initially dismissed Brigadier Winifred Bambera as a "peasant", he was able to accept her as an equal after she bested him in combat. Though his enemy Mordred accused him of having fled the battle of Camlann (in legend, the final battle between Arthur and Mordred), this may have been a bluff--during the events of DW:Battlefield, he was unflinchingly loyal to his king and his king's fight against Mordred and Morgaine.

Ancelyn displayed at least one ability unusual amongst individuals native to the main timeline: he recognised the Doctor as Merlin, on sight, despite having never met that particular incarnation of the Doctor. He also knew of the Doctor's ability to regenerate and of the TARDIS' dimensionally-transcendent interior.

After Morgaine's defeat, Ancelyn returned to his home dimension.

Behind the Scenes
King Arthur, Mordred, and Morgaine are all traditional characters from Arthurian legends. Ancelyn was invented for this serial and does not appear in the traditional body of Arthuriana; however, his father, Sir Gawain, is Arthur's nephew and one of his most trusted knights.