To me, this sounds as paranoid as the writings of Lyndon LaRouche, who believes the international drug trade is controlled by Zionists in London.
No conspiracy of this magnitude could ever succeed, because according to Poor Richard, "Three may keep a secret if two of them are dead."
British royal family, drugs, death, Lyndon Larouche, drugs again, and death again.(not to mention Zionists and London)
It would if people believed that their behavior was moral and/or ethical. If we move past a simplistic, suspense novel definition of conspiracy, one can easily see numerous examples throughout history. Oddly enough, denial is a key element that pervades this behavior.