It wasn't long before the question of Lily's origin was answered, at least.
Rescuers caught wind of a post on Facebook from Julie Galway, Lily's owner, who lives down the street from where she was found. Turns out, earlier that morning Galway discovered her garden gate and rabbit hutches had been left open under mysterious circumstances - and that Lily was missing.
With that new information, the RSPCA now thinks the incident was the work of a bunny-napper, who, for some reason, later on decided to ditch Lily on top of the house. (Plausible explanations clearly remain in short supply.)
Whatever the truth may be, however, what matters most is that she's now safe and sound.