In the gold standard era, lacking sufficient reserves of gold was unthinkable. Even though England, France, and Austria were allies, should currency reform in France run into problems, the first to take advantage of the situation would be the Anglo-Austrian two countries.
This isn't to say that other countries were on good terms with France, only that they lacked the strength to provoke France. In a world where might made right within the range of cannon fire, having a stronger fist still had many advantages.
Napoleon IV asked with confusion, "Gold prices have always been high; wouldn't that affect England and Austria too?"
Both the pound sterling and Divine Shield were gold standard currencies; as gold prices rose, the pound sterling and Divine Shield rose in value as well, and an increase in currency value would equally affect the export trade of England and Austria.