End of the Union with the ravens gone

 A Tower of London raven is missing,

that is feared dead so goes the Kingdom

 There is a  Legend  which says  that there should be at least six ravens

that they must be kept at the castle  and if not the kingdom will fall

One of the ravens at the Tower of London

 is feared to have died,

in a potentially gloomy omen

for England.

It means that the tower

is close to having fewer than six ravens,

a level that would spell doom

for the  English kingdom,

according to legend.