Heh, poor Tommy-boy really shouldn't have neglected technomagery as a source of study (I rather suspect that the engine pulling the Hogwarts Express is an early version of such thinking, using magic to refine and improve a purely mechanical system). In any case, I quite expect events to be rather surprising for Tommy-boy and his band; I also have to wonder how well they've managed to pinpoint the safe house Tommy-boy is at in order to get their launching system in position (mind you, the techie in me wonders of their using simple launching racks like early muggle efforts or if they're using more sophisticated launcher packs like the MLRS - but that's really not germane to the story). I'm going to be really interested in seeing how well this surprise attack works and, if it does, the fallout in the aftermath as various groups with widely divergent agendas clash.
BTW, Sirius only with poodlesin his animagus form? I really thought he had better taste than that. :D