Presumption in case of contravention.

Where any advertisement has been erected, exhibited, fixed, or -retained upon or over any land, building, wall, hoarding, frame, post, kiosk, structure, vehicle, neon-sign, or sky-sign or displayed to public view from a public street or public place in contravention of the provisions of this Act or the regulations made thereunder, it shall be presumed, unless the contrary is proved, that the contravention has been made by the person or persons on whose behalf the advertisement purports to be or the agents of such person or persons.