Interglacial deposits on the south side of Peterborough have yielded a diverse flora and fauna which lived in an estuarine environment that was affected by marine transgression and regression. Fossils described from six sequences indicate that the deposits accumulated under fully temperate conditions. The Woodston Beds have a diversity of fossils (pollen, plant macrofossils, molluscs, ostracods, insects and mammals) which allows their palaeoecological relationships to be examined, and compared with those of other sites of similar age. The environmental reconstructions based on the individual taxa, although emphasising differing facets of the habitat, are in broad agreement. Some slight discrepancies arise from the assumption that the organisms are characteristic of the sedimentary environment in which they are found. In fact many of the fossils have been transported to the site of deposition from nearby habitats. Evidence of a closed canopy forest with associated land environments, is provided by the plant remains and the land molluscs, and to a lesser extent by the insects and the mammals. A large, slow-flowing river, with adjacent marsh and meadow areas is also suggested by the taxa of molluscs, ostracods and insects present. Molluscs and ostracods show clearly the presence of marine influences between 11 and 14m Ordnance Datum. The climate under which the Woodston Beds were deposited was slightly warmer than the present. An age in the Hoxnian Interglacial of the Middle Pleistocene is proposed.