The dominantly nonmarine Solent Group of the Hampshire Basin, southern England, spans the Late Eocene and earliest Oligocene. It contains a rich biota, including mammals and charophytes, but contains few fully marine, time-diagnostic intervals. Correlation with standard marine successions is provided here using bio-stratigraphically significant mammals and charophytes via interdigitation of strata with those containing marine zonal indicators or via magnetostratigraphy in other parts of Europe. This allows the re-identification of recently described normal polarity intervals in the Solent Group to magnetochrons C16n, 15n, 13r1n, and 13n, and improved calibration of the Solent Group to the geomagnetic polarity time scale (GPTS). Consistent with this calibration, interpreted Solent Group sea-level changes can be related to those recognized to be global in deep-marine successions in central Italy. The major sea-level fall associated with polar ice buildup at the Oligocene isotope event Oi-1 near the beginning of the Oligocene is shown to be represented in the Hamstead Member of the Bouldnor Formation by the falling stage systems tract followed by a major hiatus before the next maximum flooding surface. This hiatus encompasses the large European mammalian faunal turnover known as the “Grande Coupure.” Improved calibration to the GPTS allows better dating of climate proxies, such that recently described summer freshwater temperatures can be shown to track global fluctuations across the Eocene-Oligocene transition.