I thought I’d dig out what information the excellent ‘Hampshire Treasures’ resource gives on this site – “Thorn Down. Tumulus group consisting of [7] bowl and disc barrows, three of which contained evidence of cremations. Centred on grid reference. O.S.A. No. SU45 NE31. Ref: 1. Proceedings of the Dorset Natural History and Archaeological Society, Vol. 1, 1870, p.197. Ref: 2. P.H.F.C., Vol. 14, 1938-40, pp.206-7.” This is a scheduled ancient monument, no.71.
A Stone Age implement was found at SU463555 – “Litchfield Down. Palaeolithic flint axe found at foot of escarpment. Present whereabouts not known”