Vol.8 of Master Keaton starts with the TV broadcasting a news segment about 'a Lion was accidentally trapped inside the cage of leopards in some zoo near River Seine.' This was later explained that it symbolizes a royal family member being in danger overseas, and is used by the British government to secretly notify the related parties (agents?)
Was this based on some real world practice?
It was certainly done during World War II by the BBC as part of Radio Londres. These were radio broadcasts from England to France, where each broadcast began with "personal messages" that were clearly coded messages for the French Resistance. Famously, it informed them of the imminent D-Day invasion.
I haven't come across any verified evidence of this on TV, though there are persistent rumors.
