The Seventh World Jamboree was held in Austria in 1951, with a special commemorative issue.

Later in the year after the Jamboree closed the stamps were used in connection with a balloon flight to the Children s camps on the Balloon Zurich on October 10, 1951.

Mail going through the Soviet occupied zone had to be censored and bear the markings and tape re-sealing of this mail where cards and letters from the free world passed through the Iron Curtain.  Note the inspection mark in the upper left corner.