A quantity of prehistoric worked flint, coarse stone and midden material was found at Rhenwyllan in 1900. The material included later Mesolithic and Neolithic worked flints, together with coarse stone implements of quartz and slate, marine mollusc shells and bone.


The original finds were discovered by Mr F. Swinnerton and included flint arrowheads, flakes and scrapers. The precise location of Swinnerton's find is not known but is thought to be along the coastal perimeter of Ordnance Survey Field no. 1635, which is centred at the grid reference provided.


More recent investigation of the area in the 1970s produced a few microliths, eight tanged and butt-trimmed flakes, eight scrapers, a flake awl of Ronaldsway type and a plano-convex knife.