She is first seen in a church that Wilf wonders into, babbling to him a story about how the Doctor once killed space satan or something. How does she know this happened? Why is she telling him this? Why is it even relevant? Never explained. Next she appears on a TV screen telling him that he should help out the Doctor or something, and then she appears to him inside the cactus spaceship telling him about what's at stake and what the Doctor needs to do next. Finally she appears behind Rassilon and makes eye contact with David Tennant, meaning she's someone important or something.