The British National Party has lost its seat on Birmingham City Council after judges ruled it was never the winner of the election.
Labour candidate Catherine Grundy has been declared the victor in the Kingstanding ward, almost three months after polling day.
But the BNP's Sharon Ebanks came second in the vote, and Labour MP Siôn Simon warned the Government must do more to reassure white working class voters that the mainstream political parties care about them.
He said: "In white working class communities like King-standing, people feel as if they are being left behind."
The final stage in the legal process ended at the High Court in London yesterday.
Two judges declared they were removing Ms Ebanks from the city council, and named Coun Grundy the winner in her place. Ms Ebanks said she would stand in the ward again at the next local elections, and was confident of winning.
It followed a chaotic election night on May 4, when the council's election officials declared Ms Ebanks the winner - before announcing they had made a mistake.
But the BNP insisted they had won the election, and the council does not have the power to take back a declaration once it has been made.
The only way Labour could claim the seat was to take legal action.
Earlier this month, a senior judge oversaw a recount and yesterday the result was officially announced.
Coun Grundy obtained 1,811 votes while Ms Ebanks obtained 1,327.
Labour's Zoe Hopkins, who came first in the poll, obtained 1,881 votes. The ward returned two councillors. In fourth place was Conservative candidate Mick Hawker, with 1,130 votes.
The results mean that the BNP, which only stood one candidate, came a clear second.
Mr Simon, whose Erdington constituency includes King-standing, said: "This catastrophic affair has finally been brought to a close. The BNP's disgraceful attempts to take advantage of an honest mis-take has finally been stopped.
"But we have to recognise that there are real issues for Labour in traditional working class areas like Kingstanding.
"White working class areas must be helped. Unemployment in Kingstanding is far too high, and that really has nothing to do with race but it creates an opportunity for the BNP to blame it on race."
Ms Ebanks said: "Anyone who was there on the night and saw the quantity of my votes would have agreed that I had won. I'm not going away, and I will stand again and win."
Simon Darby, the BNP's West Midlands organiser, said: "If that election had been carried out in the proper manner, there would have been no doubt about the result."