I find the history of Barrow Common fascinating. The large concrete buildings you probably walked past to get here, were part of a World War two radar station. There's an information board on the east side of the larger building that has some history about the installation. The smaller building used to house a generator. If you look hard enough, about 200m south of the buildings by a tree, you can find a set of four concrete footings in the bracken, that used to support the 200ft high radar mast.
The cache is next to a large pit. This might have been a chalk pit, or it might have been where a Luftwaffe bomb dropped as they tried to blow up the radar station. If you know about this, please let me know.