Clausentum

Dictionary of Greek and Roman Geography

CLAUSENTUM in Britain, the first station of the seventh Itinerary between Regnum and Londinium, distant from the former 20 miles. Ten miles beyond Clausentum lay VentaBelgarum == Winchester. This places Clausentum in the neighbourhood of Southampton, and it has been identified with that town and also with Bishop's Waltham.
[R.G.L]