While 28 boroughs use a governance system in which the councillors elect a council leader from among their numbers, four boroughs (Hackney, Lewisham, Newham, and Tower Hamlets) have a different system, in which a mayor is directly-elected by the voters to lead the council.
Directly elected mayors are the political leaders of the council and have overall responsibility for council policy and the delivery of services. Mayors appoint a cabinet of no more than 10 councillors and decide their portfolios. The cabinet can be made up of different political parties.
Councillors provide an important role in holding the executive to account by examining and questioning the decisions made. Only the full council can decide the budget and annual plans of key services.
The directly elected mayors are elected by the ‘supplementary vote’ system, with each elector asked to choose their first and second preference for the position. Voters' first preferences are counted and if one candidate gets 50 percent of the vote, then he or she is elected. If no candidate gains 50 percent of the vote, the two highest scoring candidates are recounted to determine the winner, this time including second preference votes from all other (eliminated) candidates.