Samples were taken from this site as part of a project to obtain relative dating evidence for Palaeolithic sediments in the lower Trent Valley. Amino acid racemization analysis was conducted on the remains of opercula (shells) of Bithynia tentaculata (a species of freshwater snail) identified in the sampled deposits. It was concluded that the samples from Tattershall Castle were of Marine Isotope Stage 5e age (roughly 109000 years to 123000 years before the present). {1}