David Miliband, the former Foreign Secretary who is soon to stand down as a Member of Parliament for the opposition Labour party in north-east England, resigned from the board of the Premier League soccer club at the weekend after Di Canio's appointment as manager.
"In the light of the new manager's past political statements, I think it right to step down," said Miliband, the older brother of labour party leader Ed and son of Jewish immigrants persecuted by the Nazis during World War Two.
Given his family background, with a Polish-born mother who lived through the Holocaust, Miliband's response was understandable, even if some pointed out that he is heading for a new life in America and might have given up the role anyway.
Highly combustible on and off the pitch, Di Canio has been defined for many by the fascist-style salute he delivered to the die-hard fans of Italy's Lazio club as he celebrated a derby win over rivals Roma in 2005.
Born in a working class area of Rome, the 44-year-old has in the past praised Italy's former fascist leader Benito Mussolini and has the Latin word 'Dux' - a reference to the dictator's title of 'Duce' - tattoed on his arm.
He has been open about his political sympathies. In an interview with Italian news agency Ansa in 2005 he declared: "I am a fascist, not a racist."
Even if his views may be less extreme than some of the media coverage might suggest, with Di Canio declaring in his defence on Tuesday that he is 'not a political person' and preferred to focus on football, they are undeniably controversial.
"Nobody fully understands Di Canio's politics because they involve nuances," wrote Henry Winter in Tuesday's Daily Telegraph. "What he cannot escape is the inky presence of a fascist tattoo and the photographs of a stiff-arm salute to Lazio's Ultras."
The Italian's past was an issue in his previous managerial position at Swindon Town, with the GMB trade union ending their sponsorship of the third tier club in May 2011 as a protest against the arrival of a 'fascist manager'.
"He has openly voiced support for Mussolini so it beggars belief that Swindon could have appointed him, especially given the multi-ethnic nature of the team and the town," a GMB spokesman said at the time.
The Premier League, with a worldwide reach that makes headlines of every utterance by a manager, is a far bigger platform with the capacity to magnify every controversy.
Di Canio's appointment comes also at a time of increasing popular support for the European far right as the Euro zone economic crisis deepens with a rise in anti-semitic and racist incidents at matches in countries with high unemployment.
The World Jewish Congress called in November for Lazio to be suspended from European soccer if they failed to take action against hard-core anti-Semitic supporters after Tottenham Hotspur fans were attacked.
Last month the Greek Football Federation banned 20-year-old AEK Athens midfielder Giorgos Katidis from all international teams for life after he made a fascist salute to fans.
Founded in 1879, the Wearside club - like fierce local rivals Newcastle United - is a focal point in an area once famed for shipbuilding and coal mines that was heavily bombed during World War Two with thousands of civilian casualties.
"Three hundred people were killed in Sunderland by fascist bombing whilst tens of thousands of Sunderland men would have been killed fighting fascism in Europe," Durham University professor Bob Hudson - who vowed to attend no home games while the Italian was in charge - told the Independent newspaper.
"What's been done is astonishing".
Miliband's nearby South Shields seat has been solidly Labour since the 1930s, when men and women from Jarrow marched south to London in a protest against unemployment and extreme poverty.
Di Canio's arrival drew an immediate response from the Durham Miners Association, a powerful workers' organisation, who asked for the return of a banner on permanent display at the Wearside club's Stadium of Light.
The stadium is approached along Keir Hardie Way, named after the Scottish socialist and union leader who became the first independent Labour member of Parliament in 1892.
"The appointment of Di Canio is a disgrace and a betrayal of all who fought and died in the fight against fascism," said DMA general secretary Dave Hopper. "Everyone must speak out and oppose this outrage..."
Other fans seemed less concerned, with one popular message board showing a 70 percent approval for Di Canio and only 17 percent opposed.
The club, hovering just above the relegation zone without a win in their last eight matches under the sacked Martin O'Neill, said they were disappointed by the response to the new manager and criticised those seeking to turn the appointment into "a political circus".
"Sunderland AFC is a traditional football club, with a rich and proud history," said CEO Margaret Byrne. "It has a strong ethos and ethics and that has not changed in any shape or form.
"Anyone who has met Paolo and spoken with him personally, as we did in depth before making this apointment, will know that he is an honest man, a man of principle and a driven, determined and passionate individual.
"To accuse him now, as some have done, of being a racist or having fascist sympathies, is insulting not only to him but the integrity of this football club."
Di Canio, a former Italy international who played for AC Milan as well as West Ham United and Celtic, will be keen to focus on the game and the biggest challenge of his managerial career.
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- David Miliband