There’s a superstition that if the ravens of the Tower of London are removed or leave, Britain will fall.
According to typical mythology, you’d think that the presence of ravens would imply some sort of bad fortune, rather than the absence of them. But in Britain the presence of ravens is believed to protect the Crown and the Tower. A superstition holds that “If the Tower of London ravens are lost or fly away, the Crown will fall and Britain with it.”
There are many legends regarding the origin of the ravens. For example, some say that they were attracted by the smell of the corpses of the Crown’s executed enemies. But the official story is that wild ravens were common throughout Britain and the Tower was just within their normal range.
They were exterminated from much of their traditional range and remained at the Tower in captivity and with official support. Historians have said that the “Tower’s raven mythology is likely to be a Victorian flight of fancy” (not sure if pun is intended or not).
It can also be theorized that the mythology is meant to imply the importance of the Crown more than the ravens.