Oh, yeah. This is a great way of hiding things and encoding information that only a few people will know.

For example, the BBC was an important part of the war effort since their song selection would convey secret messages to the troops, spies or POWs in Europe who knew the code. For example, the BBC would deliver secret codes in their broadcasts including letting allies know that they were about to launch a major offensive into Europe.

> The document below, from the BBC’s written archives, [sic: link to PDF] shows the unusually long list of code messages to the French Resistance broadcast on the night of 5 June 1944. It was the eve of D-Day, and the small pencilled cross next to the ninth message, indicates that it was this phrase in particular – ‘Berce mon Coeur d’une langueur monotone’ – that signalled the invasion was about to begin:

D-DAY CODES

They would also use music and other means of broadcasting information into Europe, which actually tended to go horribly wrong because it was kept secret from the general staff of the BBC that they were doing it.

The BBC had a special producer credited for song selections when it was meant to be for the Polish resistance under the name of Peter Peterkin, because the Polish news broadcast was kept short just to deliver important updates via code of musical selection.

But notes from within the BBC at that time complain about about how sometimes these vitally important updates weren't delivered because the records just weren't played because the person meant to play them didn't know they were vitally important to the war effort and ignored the given tracklist; other times, they put the recording on and it was the wrong side of the vinyl.

Interesting thing to note as well is that the BBC actually started their European news outlets this way - they would natively translate news stories and broadcast them into European languages in order to get free information out there that couldn't be supressed by the enemy. To their credit, they actually reported on their own losses in the war to intise the enemy to listen in, so that when the tides of the war turned it would actually demoralise the enemy more later on.

In the Horrible Histories book The Woeful Second World War, one woman was actually reported to the secret police because of the BBC. She was having her radio repaired after it broke down and just so happened to have overheard a news broadcast about how the son of her neighbour, believed dead in a failed military operation, was actually caught and turned over to a Prisoner of War camp. When she happily informed her neighbour about this, she was immediately arrested.

That neighbour was a cunt, wasn't she?