This set has an adhesive back, and was designed to be stuck in a special album. There is one very strange fact about this set, and that is that it was not actually issued in Great Britain first; the Channel Islands and Malta had it a month earlier, in July 1938. .
The Roald Dahl connection here is the aeroplane, a Gloster Gladiator, one of which he flew during the Second World War, and crashed in the desert in 1940 during a recce of some Italian aeroplanes. In fact he was hit not by an aeroplane but by a chance strike from an anti-aircraft gun. The aeroplane hit hard and he was badly injured, burns and facial damage, which was not helped by the fact that it took some time to find and rescue him.
Another connection is that he wrote about the crash in the Saturday Evening Post a couple of years after. It was one of his first published works.