On 6 May 2016, the day after polling day, the counting of votes cast in the elections of the Mayor of London and the London Assembly will begin.
This process will take place in three count centres across London: Alexandra Palace, Excel, and Olympia. Votes will be counted electronically.
The 14 Constituency London Assembly Members will be announced by the relevant Constituency Returning Officers. This will take place in the count centre.
The declaration of the 11 London-wide Assembly Members and the Mayor of London is made by the Greater London Returning Officer. This will take place at City Hall once all of the votes have been counted.
How the Mayoral results are calculated
The Mayor of London is elected by the ‘supplementary vote’ system.
Each voter has a first and second choice vote. If a candidate receives more than half of all the first choice votes they are elected immediately. If this does not happen, the two candidates with the most first choice votes go through to a second round. All other candidates are eliminated.
The second choice votes of everyone whose first choice has been eliminated are then counted. Any votes for the remaining two candidates are added to their first round totals.
The candidate with the highest combined total of first and second choice votes is elected as Mayor of London.
How the Constituency London Assembly Member results are calculated
The 14 Constituency London Assembly Members are elected using the ‘first past the post’ system. This means that the candidate in each constituency with the most votes is elected as a Constituency London Assembly Member.
How the London-wide Assembly Member results are calculated
The 11 London-wide Assembly Members are elected using a form of ‘proportional representation’. Votes from across London for the London-wide Assembly Members are added together. The 11 seats are then allocated based upon a mathematical formula – the ‘Modified d’Hondt Formula’. This takes into account the total votes cast in the London-wide ballot together with the number of Constituency London Assembly Member seats that each political party has already won.
11 rounds of calculations take place to fill the 11 vacant Assembly Member seats, with the party or independent candidate with the highest result at each round allocated the seat. Seats won by parties are allocated to party candidates in the order they appear on the relevant party’s list of candidates.
This voting system is used to ensure the overall Assembly reflects how all of London voted.
How your votes will be counted: e-counting
Due to the scale and complexity of the elections in London – with three ballot papers and three different voting systems – counting of the votes is carried out electronically, known as e-counting. This process has a number of stages to ensure that all votes are counted.
Once all the votes in a contest have been counted, the e-counting software will calculate the results. These calculations will be checked by the Constituency Returning Officer and the Greater London Returning Officer before being declared.
For more information about the different voting systems, download the factsheet below.