Bethan-B-Bad
Also has a journal at http://bethan-b-bad.livejournal.com/.
Practically Perfect (Doctor Who/Mary Poppins)
Reviewed by Kathryn A on 4th July 2012 (3)
Tags: Short Story, Crossover
Characters: Mary Poppins
(11K, 3315 words)
Summary: Silents in the nursery do not bode well for the future of Earth; luckily, however, there is at least one Time Lady who is willing to do what must be done. To tidy matters up.
Beautiful. This makes Mary Poppins as a Time Lord work, and still keeps her in character. Rather than being frivolous, there is depth and breadth and context. Good stuff.
Note: this has spoilers for Season Six of New Who.