End of the road ... Ken Livingstone.

End of the road ... Ken Livingstone. Photo: Reuters

Ken Livingstone has bowed out of British electoral politics after more than four decades, announcing that his unsuccessful fourth tilt for London mayor was his last election.

Exactly four years ago, Ken Livingstone's political obituary was penned by many pundits after Boris Johnson dramatically brought to an end his eight-year reign at City Hall.

Reports of his demise proved as exaggerated as Mark Twain's: within two years he had not only secured the Labour candidacy for a fourth tilt but appeared well-set to return in triumph.

But a seasoned campaigner famous for defying the odds proved unable to win even when they were stacked in his favour - neither his personal nor political magic working on Londoners.

And his defeat by the wafer-thin margin of 48.5 per cent to 51.5 per cent to Johnson prompted an immediate announcement of his decision not to stand again.

"This is my last election," he told fellow-candidates and supporters at City Hall.

"Forty-one years ago almost to the day, I won my first election on a manifesto promising to build good council housing and introduce a free bus pass for pensioners.

"Now I've lived long enough to get one myself. I didn't think I necessarily would at the time.

"And since then, I've won 11 more elections and lost three. But the one I most regret losing is this. This is the defeat I most regret, because these are the worst times for 80 years, and Londoners needed a mayor to get them through this very difficult period by cutting fares, by cutting energy prices and putting people back to work building good council homes.

"I am sincerely sorry to those Londoners who desperately wanted us to win that I failed to do that and they will continue to bear the pain of this recession without any help from here in City Hall."

Even before his announcement, it was impossible to imagine Labour - the party which once begged him to return to the fold - would ever again invest in Livingstone, 66, as the answer to its prayers in the capital.

As his campaign unravelled - in the main thanks to controversy over his personal taxes - high-profile Labour figures lined up to express regrets at his return and tell voters not to back him.

In his heyday, Livingstone was the left-wing thorn in the side of the Tories - Margaret Thatcher resorted to legislation to remove him in 1986 - as well as of Tony Blair's government, which was so determined to exclude him that it stitched up the selection process, to disastrous effect.

But he first began to blaze a trail through London politics in the early 1970s.

Within two years of joining the Labour Party in 1969, Livingstone was elected as a councillor in his native Lambeth in south London in 1971 before joining the Greater London Council in 1974.

Soon known as "Red" Ken, he was detested by the right, supporting everyone from striking miners to Sinn Fein's leaders at the height of the IRA's bombing campaign.

He famously goaded Mrs Thatcher across the Thames River in Parliament during the turbulent 1980s by hanging a banner from County Hall with the unemployment figure on it.

After she secured revenge by abolishing the GLC, he joined the ranks of Labour's left wing MPs as member for Brent East from 1987-2001, harrying the Tories but also clashing frequently with the New Labour modernisers.

When Blair restored devolved government to the capital - and created the powerful post of mayor - he did not anticipate that it would open the door for his foe's return.

Livingstone stood as an independent against official Labour candidate Frank Dobson in 2000 and won. Such was Livingstone's popularity that Mr Blair was forced to welcome him back into the fold and ensure he was the official Labour candidate in 2004.

During that second term, Mr Livingstone won widespread praise for the way he stood up for London after the July 2005 suicide bombings and helped win the 2012 Olympic Games for the capital.

But his momentum during his last campaign was dramatically arrested by a row over claims he set up his business affairs to avoid paying large sums in income tax - and his refusal to publish accounts in full.