There is little archaeological information available for the site, but the reserve does contain what is thought to be a Bronze Age burial mound c1800-550BC. This mound and an additional tumulus to the south of the site gives some indication of past land character. Such burials were generally placed in open country and this probably indicates that the area was open heathland at that time.
There is an extensive network of banks in the western half of the site. These may vary in age and are very difficult to interpret in terms of function and date of construction. Some may have been woodbanks or boundary banks. Part of the boundary bank of the Saxon Hundred of Crondell, an administrative and judicial unit of several parishes, was previously thought to be on Castle Bottom but is now known to be some distance to the south, adjacent to the A30. A rectangular banked feature on the northern boundary may have been an enclosed garden associated with the cottages in the same area. Despite the name there is no evidence of a castle on or near Castle Bottom!
There are the ruins of two cottages on the northern boundary of the site, which were inhabited until the early 1960’s. It is not known exactly how old these are but they are known to predate the 1930’s. A former resident of the cottages provided a written account of life on the heathland which was subsequently published in Eversley Parish Magazine. An annotated map featuring wildlife and topographical features further depicts Castle Bottom during the 1920/30’s. There is also a hand-drawn map of the area as it appeared to them between 1925 and 1935, annotated with wildlife and topographical features.
The cottages were sold in 1952 along with the rest of the land, which was part of the large Bramshill Estate. The land on Castle Bottom was described as being suitable for pig farming, small holdings or re-afforestation. Some of the boundary banks are planted with Holly, a feature sometimes associated with grazing. It is possible therefore that much of the site was used for rough grazing. An attempt to improve the commercial value of grazing on the site was made in the 1950’s, the central area being cleared, limed and sown with Cock’s-foot.
Before the County Council bought the site, it was owned by Wilkinson Rubber Linatex, manufacturers of quarrying equipment. Their apparent intention was to use the site for testing extraction equipment, but there is no evidence of this haven taken place.