Malicious Damage Act 1861

According to the Fourth Doctor, the  applied to lighthouses. He told Leela this after she had broken through the door to Reuben's room with a sledgehammer. (DW: Horror of Fang Rock)

Behind the scenes
The law is indeed a real one, and it probably could be applied to lighthouses. However, it does not appear to specifically mention lighthouses, only damage done to buildings in general.