One theory I've heard is that it is just Sir Ian Blair being demob happy on his last day in the job at the Met. He certainly has no reason to love the Tories.
Another possibility is simply that the information being leaked on this occasion was genuinely something a bit sensitive that someone decided had no business being leaked - I can imagine Ministers making very clear that they did not want to know about something which might be needful but awkward.
Another possibility is that there was some element of bribery involved - not financial, because the charges are not bribing a civil servant, but misconduct in a public office. An evil imp keeps demanding that I hope that the bribery involved involved the Shadow Minister's less than luscious body - but that would be so very wrong.
Of course, all of the above could be true at the same time. If it damages the Tories, that'd be good; if it damages Jacqui Smith, well, that would not break my heart either.
Jacqui Smith's new best friend, Julie Bindel, is at it again in g3, painting herself as the innocent victim of teh evil trans. It really is remarkable how many lies that woman will tell, and presumably convince herself of, in public.