Labour stake all on figure from past
Given that the usual laws of political gravity have not applied much to Ken Livingstone until now, it would be foolish to rule out yet another theatrical comeback.
But by selecting him, Labour members have staked their party's future in the capital on a figure viewed as from the past.
Livingstone will always be able to draw on a core of support and affection from people who think he revived the capital when it was down and out.
But it will take more than that to give him another chance in City Hall.
"Ken is going to have to present himself as new," said Tony Travers from the London School of Economics.
"He is going to have to find ways of repositioning and renewing himself for the electorate, particularly for older people and outer London."Mayoralty snatched
The 2008 contest with Boris Johnson will now be reprised.
Livingstone clings to a belief the mayoralty was snatched from him not because of his waning popularity but because of Gordon Brown's leadership and a government in freefall.
Indeed, the million-plus first and second preference votes he received in 2008 were more than those he secured when he won in 2000 and 2004.
And his 37% share ran well ahead of Labour's national showing.
Supporters think Ken Livingstone will be ideal to fight coalition cuts as mayoral candidate
However, it is open to question how much this represented a vote for him rather than a vote for Labour whose support in the capital had been consistently resilient since 1997.
The swing in the vote share from Ken Livingstone to Boris Johnson was more than 6%, compared to a swing of less than 2% from Labour to the Conservatives in the London Assembly vote.
Nevertheless, the failure of other major Labour figures to enter the selection race testified to Livingstone's entrenchment, and his appeal to the unions.
Few fancied the risk of a messy outcome if they took him on.
Oona King, though, did take the plunge and received the backing of several shadow cabinet members.
Whether she has enhanced her future prospects remains unclear.
She hoped to make a virtue of her gender and youth, praising Ken Livingstone for his past impact but insisting it was imperative Labour looked forwards.Inner city interests
King also distanced herself from her rival's stance on cuts to public services, stressing she was seeking practical solutions rather than confrontation.
While Livingstone was careful not to attack her, King repeatedly endorsed the view that the "zone one" mayor had alienated the suburbs.
The sub-text was that Livingstone had for too long promoted the interests of a predominantly inner city multicultural powerbase, believing loyalty and numbers would always stack up for him.
They may have continued to do so, but for the lethal combination of a lame-duck Labour prime minister and a charismatic opponent who stirred up the resentments of outer London.
In the wake of Livingstone's defeat, senior Labour figures were adamant he would not run again - even as he started ominously attending City Hall meetings to watch his successor close-up.
As he quickly demonstrated he was not ready for enforced retirement, it was said senior (and in the past supportive) party figures would be sent to implore him to leave the scene quietly in the interests of the party, to allow new life to breathe.Mischievous grin
Yet Labour's general election defeat and the looming economic choices provided him with a perfect platform to mount a re-run.
It also forced party members to think hard about the mettle required in a candidate now certain to be at the heart of the unfolding narrative of spending cuts.
He may wear an expression nowadays more hangdog than the mischievous grin with which he taunted Margaret Thatcher a quarter of a century ago but his supporters say his passion and energy are undiminished.
It may be, though, that Boris Johnson will relish a contest in which Livingstone is portrayed as reprising his 'Red Ken' role.
But in the end the message from Labour in London has gone out: Send for the man who's been it, seen it. And hope he can weave his magic one more time.