The London mayoral election for the office of Mayor of London takes place quadrennially. The first election was in held May 2000, and four subsequent elections have taken place. The latest mayoral election took place in 2016.
London mayoral elections Wikipedia
The electoral system used for London mayor elections is the supplementary vote where voters express a first and second choice of candidate, if no candidate receives an absolute majority of first-choice votes, all but the two leading candidates are eliminated and the votes of those eliminated redistributed according to their second-choice votes to determine the winner.
As with most elected posts in the United Kingdom a candidate must pay a deposit to run in the election. The current deposit a candidate must pay is £10,000 which is returned if the candidate's wins at least 5 percent of the first preference votes cast. The Winner is elected for a fixed term of four years, there are no restrictions on the number of terms a Mayor may serve. Elections take place in May.
The 2016 London mayoral election was held on 5 May 2016. The results were announced on 7 May at 00:30 despite British TV news channel Sky News announcing Sadiq Khan as the winner hours earlier.
Incumbent Mayor Boris Johnson did not run for re-election for a third term in office, as he was elected the Member of Parliament for the Conservative Party in Uxbridge and South Ruislip in the 2015 general election.
Conservative Mayor Boris Johnson was reelected to a second term in office, defeating former Labour mayor Ken Livingstone. Livingstone announced his retirement from politics in his concession speech.
The incumbent Labour Mayor, Ken Livingstone was defeated by Conservative candidate Boris Johnson who became London's 2nd Mayor.
In 2004, the second election was held. After being re-admitted to the Labour Party, Ken Livingstone was their official candidate. He won re-election after second preference votes were counted, with Steve Norris again coming second.
The 2000 campaign was incident-filled. The eventual winner, Ken Livingstone, reneged on an earlier pledge not to run as an independent after losing the Labour nomination to Frank Dobson. The Conservative Party candidate, Jeffrey Archer, was replaced by Steven Norris after Archer was charged with perjury.