A Shadow Government is a secret "government in waiting" that remains hidden with the intent to take control of the government should a crippling catastrophe occur.
The Civil Contingencies Secretariat is responsible for planning for government continuity in the event of catastrophe, although it is not itself a "shadow government"
... appeared in Italian (Venice, 1488,
Milan 1489), Spanish (Seville, 1536), Arabic (Rome,
1663), Armenian (Rome, 1674), Hebrew (Frankfort,
1837), and other languages. ...