The man, who has not been publicly named, was taken to Colnbrook Immigration Removal Centre on 28 January and left the country on 7 February.
"From my understanding the wait for the lawyer in the centres is ridiculous," said Fay Howard, a Labour councillor from Swindon. "It can be up to a couple of weeks and by the point he had one scheduled, he had been deported."
Detainees at immigration removal centres are entitled to free legal advice under the Detention Duty Advice Scheme but demand for appointments is high.
They "may have to wait up to two weeks or longer before being able to see a legal adviser," a recent parliamentary report stated. "Those detained on the grounds that their removal is imminent may be removed before that."
The man, who is in his mid-twenties, was trafficked into the UK on two occasions by gangs and had been in the process of applying for asylum.
He was partly supported by a scheme run by Swindon City of Sanctuary, a campaigning group which which pairs refugees and asylum seekers with local hosts.
He lived with Ms Howard and her family between July and October 2018.
"He was lovely," she told The Independent. "He was very vulnerable and quite meek. He helped out around the house a lot - too much, I'd say. He was very guarded but he liked cooking. He liked playing table tennis with my son."
Ms Howard said that her husband and children visited the man at the detention centre the night before his removal.
"He was really frightened," she said. "There isn't the same support for male victims as there is for girls. They're just as vulnerable."
Nicola Wood, City of Sanctuary's executive officer said "the current system does not protect those who have been forced into modern slavery."
She added: "The Home Office has let down a young man who has suffered a lot and was finally finding support, friendship and love in Swindon. Someone who was following a legal process. He's now been taken away, without much explanation, having been let down by the system that we believe should be protecting him from being re-trafficked.
"To regain the trust of the public, the Home Office urgently needs to restore legal aid for immigration cases and end immigration detention."
The Home Office was approached for comment.
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