Update, May 7, 00.25am: Sadiq Khan has been formally declared the new Mayor of London.

After a delay of about six hours, the Labour candidate was declared the victor, with a total of 1,310,143 votes, first and second preference.

Zac Goldsmith was pushed into second, with 994,614 total first and second votes.

In a victory speech, Mr Khan said: "Thank you, London.

"I'm so proud of our city.

"I'm deeply humbled by the hope and trust you have placed in me."

He thanked voters for choosing "hope over fear and unity over division"

He said: "Fear does not make us safer and the politics of fear is not welcome in our city."

He promised to "always be a mayor for all Londoners". 

From earlier: Sadiq Khan has won the London Mayoral race as sources in City Hall confirm it is impossible for Zac Goldsmith to make up the numbers.

With 90 per cent of first preference votes verified earlier this evening, Mr Khan had a nine point lead.

The final results have not been confirmed at City Hall. 

Mr Khan was ahead in the polls throughout the campaign, and early indications on count day put him at least 10 points ahead of his Conservative rival.

Despite the lack of official announcement, congratulations are coming in from across the globe.

Labour candidates have taken nine of the 14 constituency seats in City Hall, including an upset in Merton and Wandsworth, which had been Conservative since 2000. 

In 2012, Boris Johnson received a total of 1,054,811 votes, made up of 971,931 first preference and 82,880 second preferences.

More to follow.