Labour's Sadiq Khan has been elected as Mayor of London defeating his Conservative rival, Zac Goldsmith.

Khan is London's first Muslim mayor and triumphs after a racially divisive campaign where Goldsmith repeatedly labelled him an extremist. Goldsmith's allegations were repeated by the Prime Minister but were branded a "repulsive campaign of hate" by Labour leader Jeremy Corbyn.

Khan won with 1,310,143 votes, or 57 per cent, after second preferences were taken into account. A number of commentators pointed out this gave Khan the biggest indidividual mandate for a politician in history. Goldsmith was left with 994,614, or 43 per cent of the vote. 

In his victory speech Khan said: "I am so proud that London has today chosen hope over fear".

He continued: "I hope that we will never be offered such a stark choice again. Fear does not make us safer, it only makes us weaker, and the politics of fear is simply not welcome in our city."

Khan referred to his origins on a council estate in south London and said he never imagined "someone like me could be elected as mayor of London". 

Goldsmith joined outgoing mayor Boris Johnson in congratulating Khan and wishing him well. 

Elsewhere in the UK, the Scottish National Party (SNP) won a third successive election in Scotland but failed to gain enough seats for a majority.

But the shock result in Scotland was that the Conservatives beat Labour to become the country's official opposition. Ruth Davidson, the Scottish Tory leader, oversaw a successful campaign after years of defeat for Conservatives north of the border.

Davidson promised to "hold the SNP to account" and say "no to a second independence referendum".

Nicola Sturgeon, leader of the SNP and Scottish First Minister, said the party's 63 seats out of 129 gave the party "a clear and unequivocal mandate" to govern as a minority administration.

On the issue of Scottish independence, a key aspect of the SNP's identity, Sturgeon said her aim was to "persuade, not to divide". She said her party would "our case with passion, with patience but will always respect the opinion of the people".

In Wales Labour fell just short of a majority with Plaid Cymru beating the Tories to take second place. UKIP had a good night winning seven seats at the Welsh Assembly.

Compared to the last regional elections in 2011, Labour's share of the vote was down 9.2 percent in Scotland and 7.6 percent in Wales, allowing a strong showing for UKIP.

Labour leader Jeremy Corbyn insisted his party had "hung on" and "grew support in lots of places".

The Tory vote share fell across southern England, allowing Labour to retain control of several key seats such as Crawley, Southampton, Norwich and Hastings.

On Friday David Cameron said: "Local election day for sitting prime ministers is supposed to be a day of dread, waiting for the knock on the door like a condemned man waiting for a hangman.

"But that's wasn't what it was like last night."

Thursday's polls were the largest test of public opinion before the 2020 election with 43 million people entitled to vote across 2,747 seats in English councils alone.