Teesside the four independent unitary authority boroughs of Hartlepool, Stockton, Middlesbrough and Redcar and Cleveland (a renamed Langbaurgh). At this time they were returned to the counties of North Yorkshire and County Durham for ceremonial purposes, with Stockton-on-Tees becoming the only district in England split between two ceremonial counties. In 1998 the neighbouring Borough of Darlington also became an independent unitary authority and this along with the four former Cleveland boroughs form the sub-region of the Tees Valley which is used for statistical purposes and governmental organisation. The name Tees Valley is increasingly promoted for economic and cultural connections, though Teesside,
Teesside Refinery Teesside Refinery The Teesside Refinery was an oil refinery and chemical plant situated just south of Seaton Carew on the River Tees in County Durham. In 2000, it was bought by Petroplus from ICI and Phillips Petroleum Company. Refining was suspended in 2009, although the site continues to operate as a terminal and storage facility. In the period 1965-1968, three oil refineries were developed close to Teesport on the River Tees, thanks to the Phillips Petroleum's development of the Ekofisk oil field in the North Sea. The first two were jointly developed and operated by Phillips and ICI on the