The four-time Olympic champion's revelations will also put pressure on authorities to ensure that those who are exploited by traffickers are treated as victims, not criminals to be deported, an immigration expert has said.
“I don’t think there’s ever been a case in British public life where somebody so familiar to the British public… reveals how dark, how difficult, how complex his back story is,’’ said Sunder Katwala, director of British Future, a nonpartisan think tank on identity and immigration.
“We rarely have the voices and faces of people trafficked, but for it to be one of the most familiar public figures of Britain in this century is truly extraordinary.”
Mr Katwala said Sir Mo's story also has the potential to create the safe space necessary for other trafficking victims to seek help - just as entertainers and athletes who came out as homosexual bolstered the gay rights movement.
Charity workers, lawyers and others who help victims of modern slavery also praised Sir Mo’s courage in coming forward and said the publicity will help bring humanity to the debate.
Many victims, they say, struggle for years to escape and overcome the trauma caused by their exploitation.
“To know that there is someone, as tragic as it is, who has gone through it, come through, and been able to be successful in his chosen field and to speak from lived experience is an immensely important thing,’’ said Ryna Sherazi, director of fundraising and communications at Anti-Slavery International.
The father-of-four, 39, revealed in a BBC documentary that his real name is Hussein Abdi Kahin and he was born in Somaliland, a breakaway region of Somalia ravaged by war during his childhood.
He was trafficked illegally under the name of another child when he was nine years old.
He said he decided to speak out about his experience in the hopes of challenging public perceptions of trafficking and modern slavery.
Until this week, Sir Mo had said he came to Britain as a refugee with his family. That is the story he told UK immigration officials when he became a citizen in 2000 at the age of 17.
He went on to represent Great Britain at three Olympic Games, winning gold in the 5,000- and 10,000-meter runs in both 2012 and 2016. He was knighted by Queen Elizabeth II in 2017.
Despite his fame and success, Sir Mo said he feared he would be deported if he ever told the truth about how he came to Britain.
The athlete said he was "relieved" that the Home Office confirmed it would "absolutely not" be taking any action against him.
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The UK Home Office has the power to legally strip individuals of their British citizenship if it is found to have been obtained illegally.
Rob McNeil, deputy directory of The Migration Observatory at the University of Oxford, said Sir Mo’s story is unlikely to change UK policy on its own - but it helps shift the debate by humanising the abstract idea of an “illegal immigrant.”
“Policy narratives about irregular migrants typically deal with them as a sort of homogenous group of ‘wrongdoers’ and a problem to be solved, rather than individuals at risk,’’ he said.
“A softening of the UK’s rhetoric and policy toward irregular arrivals seems likely only if the wider debate becomes more focused on the people who are being targeted, rather than the policy failures they represent.”
More than 10,000 people were referred to British authorities as possible victims of modern slavery in 2020, up from 2,340 in 2014, according to a report from the Home Office.
The Home Office has often faced backlash for its approach to migrants, refugees, and asylum seekers - with the controversial recent policy of deporting "illegal" immigrants seeking asylum in the UK to Rwanda the subject of several legal challenges.
Outgoing Prime Minister Boris Johnson says the Rwanda plan will break the business model of criminals who smuggle people across the English Channel in small boats, immigrant advocates say the plan is illegal and inhumane.