Borisashton wrote: It should also be added that Russell T Davies has stated that at least Harriet Jones, PM is canon. In fact the full quote is "It's a BBC Book that makes it canonical. She is alive." Although I am perfectly aware that this wiki has no canon what it does show he intends that these events did happen. He also states that producer Phil Collinson said on set that Harriet wasn't really dead and T Davies illustrated what he had said in the poem.
Considering that Russell T. Davies has never made such definitive statements about 'canon' and that the illustration depicts Harriet Jones dropping down a trapdoor, bouncing off a trampoline and onto a motorcycle and driving away, I'd say that he was joking.