Industrial port and administrative centre of Middlesbrough unitary authority in northeast England, on the estuary of the River Tees, 35 km/22 mi south of Sunderland; population (2001) 142,700. The modern town only started to develop in the early 19th century after it was decided to extend the railway to reach deeper anchorage on the river: this allowed the town to become a centre for heavy industry. It diversified in the 1960s into construction, electronics, engineering, and shipbuilding. History Middlesbrough was still only a farm of 25 people as late as 1801; the town did not start to grow until 1829 when a group of Quaker businessmen, headed by Joseph Pease of Darlington, purchased the farm and developed the ‘Port of Darlington’. A town was planned on the site of the farm to supply labour to the new port. Pease was the son of Edward Pease, who had developed the Stockport–Darlington railway, and when this line was extended by 6 km/4 mi in 1830 to Middlesbrough, the town and port…