Simplify the following text for a Grade 11 native English-speaking person.
Original: In 1974 the administrative county and the county boroughs were abolished by the Local Government Act 1972 and County Durham was reconstituted as a non-metropolitan county . The reconstituted County Durham lost territory to the north east ( around Gateshead , South Shields and Sunderland ) to Tyne and Wear and to the south east ( around Hartlepool ) to Cleveland .
Simplified: In 1889 the administrative county of Durham consisted of the historic county less the county boroughs of Gateshead , South Shields and Sunderland .