Many British Prisoners of War were able to send messages back to the UK, using coded letters or hidden messages. Here a letter from Flying Officer Peter Tunstall and Wing Commander Douglas Bader has been concealed inside a photograph. The photographic paper has been carefully split and the message - written on a sheet of tracing paper - inserted. Note how the writing follows the dark part of the image, to ensure that it remains hidden.
The typescript copy identifies the letter as the third sent by this means. A later letter was discovered by the Germans before it could be sent. Both Bader and Tunstall were arrested and charged with spying, but the charges were dropped.