Inconclusive conclusions

I read a book last week. It was Roald Dahl's 'Beware of the dog'.  I pride myself on being an avid reader and it was really embarrassing for me to finish a story and not understand the ending. For the uninitiated, the story is about an fighter pilot in WW2 who is injured in action. He wakes up in a hospital and soon begins to suspect that he is in enemy territory. Although the doctors seem to be British like himself and they tell him they are in England, there are minor details that bother him like the hardness of water in the region, the nurse with shifty eyes and the sound of German fighter planes. He painfully gets to a window on one leg, and upon looking outside, sees this sign on an adjacent property, "garde au chien" which is french for 'beware of the dog'. Anyway, he remembers something his commander told him about not revealing anything more than his name, rank and squadron number in the event of capture. So, when the an officer comes to take his statement about the accident, he tells him just these three things. And there the story ends abruptly.

See, this could mean one of many things. He might have been captured by the enemy, who were trying to deceive him. If that was the case, he had done the right thing by not telling them anything. On the other hand, what if he was just delusional from the loss of blood (and one limb)? Besides, wasn't France a part of the allied forces? I couldn't rest till I found out what the author intended, so I did a google search and found a site with a discussion about this story. What I found out was that he had left the rest of the public as confused as myself. Maybe this is one of those stories where you are expected to draw your own conclusion. Well, I guess this will be eating my head for quite a while.