The ceremonial county of Essex, which includes the unitary authorities of Southend-on-Sea and Thurrock, has returned 18 MPs to the UK Parliament since 2010. As a result of the creation of Greater London under the London Government Act 1963, which came into effect on 1 April 1965, the boundaries of the historic/administrative county were significantly altered, with the south-western corner, representing a majority of its population and seats, being transferred to Greater London, forming the London Boroughs of Newham, Barking and Dagenham, Havering, Redbridge and Waltham Forest. This was reflected in the following redistribution of parliamentary seats which came into effect for the February 1974 general election and effectively reduced the county's representation from 26 to 12 MPs.