Tap above to watch video report by Simon Harris
Sadiq Khan will learn tonight if Londoners have elected him to serve a second term as mayor.
Counting resumed on Saturday after results from seven of the 14 London Assembly 'super' constituencies were declared on Friday.
Data from the electronic counting machines revealed a much tighter contest than expected between the Labour mayor and his Conservative rival Shaun Bailey.
The overnight tally showed Khan won 39% of first preference votes with Bailey winning 37%. Green Party candidate Sian Berry was in third place with 8%.
Labour hopes of an outright victory by winning more than 50% of the vote were dashed. The outcome of the election is likely to be decided by second preference votes.
Khan had a commanding lead in pre-election opinion polls and remains favourite to win.
Labour held on to four assembly seats - Brent & Harrow, Ealing & Hillingdon, Lambeth & Southwark and North East. The Conservatives were returned in Bexley & Bromley, Havering & Redbridge and West Central.
The result of the mayoral contest will be announced after the final seven assembly assembly seats are declared.
Candidates have been told by officials not to arrive at City Hall for the results before 8pm.
Ballot papers were being counted at three election hubs - Alexandra Palace, Excel and Olympia.