County Borough of Teesside councils in 1918, and was a pioneer operator of electric trolleybuses. The three undertakings adopted a common livery of turquoise and cream in 1967 in preparation for their amalgamation. On 1 April 1968 the combined fleet became Teesside Municipal Transport. Teesside initially operated a mixed fleet of trolleybuses and omnibuses, but on 4 April 1971 trolleybus operation ended. A formal closure ceremony was held two weeks later. Before 1968 the Teesside area was served by three police forces: Middlesbrough Borough Police, Durham Constabulary and the North Riding of Yorkshire Constabulary. It was originally envisaged that the new county borough would
County Borough of Teesside of the proposed county of Cleveland were considerably altered, with a number of marginal areas removed. Under the revised scheme, the Teesside district would have 70 percent of the county's population, and it was felt that it would dominate the county. Accordingly, new guidelines were issued to the Local Boundaries Commission in March 1972 that was charged with drawing up district boundaries: Cleveland ""should be divided into not less than four new districts with populations comparable as is reasonably practicable having regard in particular to the pattern of local government before the establishment of the Teesside county borough"". The county