I recently heard tell that, during the second world war, American forces were stationed nearby. Needing storage for trucks etc. they decided that a good place would be the old hillfort. They also decided that the western entrance, which had served well in the old horse and cart days wasn't wide enough for their purposes. With the 'can do' attitude for which Americans are renowned, they apparently sent up a team of engineers to widen the entrance. They had made a good start and flattened a section of the outer bund before someone realised that the hillfort was an ancient monument and called a halt to operations. I don't know for certain that this account is true. However, in these images
SU1476 : Barbury Castle Hill Fort, near Swindon - western entrance, another angle and
SU1476 : Barbury Castle Hill Fort, near Swindon - western entrance it is possible to discern the flattened area. If anyone can either confirm or debunk the story, please feel free!