By chance I watched the episode today and whilst full of 'talking heads' that had been spliced in to state the obvious, there were interesting facts about Nazi activity in the area (Gran Canaria) and sightings by fishermen of soldiers on the beaches at times and semaphore signing from U-Boats toward the Villa Winter. It's construction was very substantial, especially underneath the main house. It reminded me of the bunkers and U-Boat pens that I've been in in the past. This would give strength to the possibility that the airstrip of this thread was used initially and primarily by the Nazi regime for purposes as yet unclear.