Twenty-fi ve million years ago, well after the rough contours of the British Isles had already been revealed, the chalk land to the north of the Solent at its eastern end was tilted upward, creating the distinctive feature of Portsdown Hill as part of the South Downs. In the past 2 million years, the oscillations in sea levels of the interglacial period began to give fi nal shape to the landscape in the South Hampshire area. In the fi nal post-glacial period, the coastal plain, which had previously been continuous and formed the northern bank of what was the Solent river, became punctuated by rivers and marine inundation into a series of islands, peninsulas and river valleys (Daley and Carter, 1989; Haskell, 1989). The value of the natural harbours and tidal river valleys to commerce and defence, coupled with its amenity, meant that this stretch of coast had a long history of settlement dating back to pre-Roman times. From medieval times, the two established cities of Portsmouth and Southampton grew around military and commercial port-related activities to become signifi cant urban centres within the South East of England distinct from, but connected to, the capital, London.