The county council was formed in 1889, governing the administrative county of Essex. West Ham, otherwise part of Essex at the time, was a county borough and therefore outside the area of responsibility for the county council. Southend-on-Sea (1914) and East Ham (1915) were also removed. In 1965 Barking, Chingford, Dagenham, Hornchurch, Ilford, Leyton, Romford, Walthamstow, and 'Wanstead and Woodford' were transferred to Greater London. The county council was reconstituted in 1974 as a non-metropolitan county council, regaining jurisdiction in Southend-on-Sea, however the non-metropolitan county was reduced in size in 1998 and the council passed responsibilities to Southend-on-Sea Borough Council and Thurrock Council in those districts. For certain services the three authorities co-operate through joint arrangements, such as libraries and the Essex fire authority.
