Send three'n'fourpence, we're going to a dance...

I'm sure you've probably seen the story of the skeleton of a world War II carrier pigeon which was found recently in a chimney down in Surrey with a coded message still attached to its leg.  Since when all attempts to decipher the message have proved fruitless.  Not surprising really - almost certainly the message was coded using a "one-time pad" and such messages are literally impossible to decode without a copy of the pad that was used, which of course has almost certainly been consigned to the shredder or the furnace decades ago.