The Matrix Archives/Mrs. Potts (Bill's mother)
From Tardis Wiki, the free Doctor Who reference
How do we treat Mrs. Potts in cast sections and appearance sections in infoboxes? Is she a recurring character given her pictures appearing in The Pilot, Knock Knock and as a flashback in Oxygen and then later she appears in person in The Lie of the Land, even though it's imagined by Bill.
