There were previously a number of local authorities responsible for the Merton area. The current local authority was first elected in 1964, a year before formally coming into its powers and prior to the creation of the London Borough of Merton on 1 April 1965. Merton replaced the Municipal Borough of Mitcham, the Municipal Borough of Wimbledon and the Merton and Morden Urban District, all formerly within Surrey. It was envisaged through the London Government Act 1963 that London local authorities would share power with the Greater London Council. The split of powers and functions meant that the Greater London Council was responsible for "wide area" services such as fire, ambulance, flood prevention, and refuse disposal; with the local authorities responsible for "personal" services such as social care, libraries, cemeteries and refuse collection. This arrangement lasted until 1986 when London Borough Councils gained responsibility for some services that had been provided by the Greater London Council, such as waste disposal. Since 2000 the Greater London Authority has taken some responsibility for highways and planning control from the council, but within the English local government system the council remains a "most purpose" authority in terms of the available range of powers and functions.
Merton is divided into 20 wards, each electing three councillors. The political voting patterns in Merton broadly follow the geographical divide between Merton's two UK Parliament constituencies. The eastern Mitcham and Morden constituency, which is held by Labour MP Siobhain McDonagh, contains ten wards and has only ever elected Labour councillors. The western Wimbledon constituency, which is held by Conservative MP Stephen Hammond, contains ten wards and usually elects Conservative councillors, of which there are presently 17. Since 1990, the ward of Merton Park has only ever returned councillors for Merton Park Ward Residents Association. Since 1994, the ward of West Barnes, which contains Merton's half of the town of Motspur Park, has swung between the Conservatives and the Liberal Democrats; the latter presently hold all three seats in the ward. In the local elections in 2018, Liberal Democrat councillors were elected in the wards of Trinity and Dundonald for the first time in the borough's history, bringing the party's seat numbers to a record of six seats. Furthermore, the wards of Abbey and Cannon Hill routinely return Labour councillors. Since 1964 political control of the council has been held by the following parties:
Party in control
Years
No overall control
1964–1968
Conservative
1968–1971
Labour
1971–1974
Conservative
1974–1989
No overall control
1989–1990
Labour
1990–2006
No overall control
2006–2014
Labour
2014–Present
Leaders
The following have served as leaders of Merton Council since its formation:
Mayors
At the Annual Council Meeting, a mayor is elected to serve for a year. At the same time, the Council elects a deputy mayor. Since 1978, each Mayor must also be an elected councillor. The Mayor also acts as the ceremonial and civic head of the borough during his/her year of office and the post is non-political. Each year the Mayor also chooses two charities which will benefit from a series of fundraising events throughout the mayoral year. The following have served as Mayor since the formation of the Borough in 1965 and reflects their status on the council at the time they were elected as Mayor:
