Boris Johnson passes the winning post – but it was no easy ride to victory

Johnson seals second term as Mayor by narrow margin amid chaos counting the votes

Boris Johnson clinched a narrow victory last night as the battle to become London Mayor reached a dramatic and chaotic finale. The Conservative incumbent saw off Ken Livingstone's bid to return to City Hall with a slim majority, beating his Labour challenger by 51.53 per cent to 48.47 per cent.

Mr Johnson just made it across the finishing-line once second-preference votes were redistributed. But the count was mired in controversy after it was delayed for hours by the discovery of two boxes of uncounted ballots from Harrow and Brent in north-west London.

When the results were finally declared at 11.55pm, the Green candidate Jenny Jones secured a personal triumph by finishing third, followed by the Liberal Democrat Brian Paddick and the independent Siobhan Benita.

The last-minute drama followed an acrimonious campaign in which the two front-runners – reprising their contest of 2008 – swapped insults.

Mr Johnson's team had focused on his challenger's controversial tax arrangements, while Labour responded by branding the current Mayor a joker who had distanced himself from his party.

Polls on the eve of the election gave Mr Johnson a six-point lead. But as the votes were tallied yesterday, it became clear the gap between the long-standing foes was much narrower than expected.

An agonising wait ensued for the Tory and Labour teams as the uncounted ballots were discovered, problems emerged with the electronic counting machines and a counting centre suffered a power cut.

Labour sources, who had previously conceded defeat, suggested supporters who disliked Mr Livingstone had not been able to bring themselves to back his Tory rival when the reached the voting booth.

Mr Johnson plans to kick off a second term with a reshuffle of his senior team and by ordering hundreds of new Routemaster buses for the capital.

His re-election in Labour-leaning London would have a wider significance in Conservative politics as it would establish him as the obvious successor to David Cameron.

The Independent disclosed yesterday that the Mayor's allies expect him to stand for Parliament at the next general election, which is due in 2015.

Under this scenario, he would combine the roles of Mayor and MP for one year before returning full-time to national politics.

For Mr Livingstone, his defeat marks the end of political career dating back to the 1960s. He protested yesterday that the campaign had been "dominated by smears and trivialities".

Results: Electorate 5,804,790, turnout 2,208,475 (38.05%, -5.81%)

First Count

Boris Johnson (C) 971,931 (44.01%, +0.81%)

Ken Livingstone (Lab) 889,918 (40.30%, +3.30%)

Jenny Jones (Green) 98,913 (4.48%, +1.28%)

Brian Paddick (LD) 91,774 (4.16%, -5.64%)

Siobhan Benita (Ind) 83,914 (3.80%, +3.58%)

Lawrence Webb (UKIP) 43,274 (1.96%, +1.03%)

Carlos Cortiglia (BNP) 28,751 (1.30%, -1.58%)

Eliminated: Siobhan Benita, Carlos Cortiglia, Jenny Jones, Brian Paddick, Lawrence Webb

Second Count

Distribution of Benita's, Cortiglia's, Jones's, Paddick's and Webb's votes:

Boris Johnson (C) 1,054,811

Ken Livingstone (Lab) 992,273

Elected: Boris Johnson

Huge Labour gains leave Coalition with identity crisis
Boris Johnson passes the winning post – but it was no easy ride to victory
'Red Ken' finally reaches the end of the line
Clegg punished with his party's worst-ever results
MPs turn fire on Cameron after dismal showing
Labour takes power across the country – and Miliband tightens grip on his party
Leading article: A good result, but Labour must beware a false dawn
Steve Richards: Labour (and Ed Miliband) are no longer doomed
Andrew Grice: Bruised and battered, Clegg will struggle to sell Coalition relaunch
Professor John Curtice: Labour's making progress, but it's still some way from No 10
Chris Bryant: The naked and the dead – just a couple of the things you meet while canvassing
Galloway's Respect wins in Bradford again
'Chipping Norton set' desert the Tories
Cities reject Cameron's dream of mayors for all
Salmond setback as Scots nationalists fail in Glasgow