An asylum seeker who claimed he was 15 and joined a Year 11 class at a secondary school is now being treated as an adult.
An investigation was launched earlier this month when children at Stoke High School in Ipswich raised concerns about the age of a new student, who enrolled in September.
The question of his age came to light when students sent Snapchat photographs of the man with the caption "how's there a 30-year-old man in my maths class?"
The Home Office has now confirmed that an age assessment, completed by the local authority, has verified that the man is over the age of 18.
A spokesperson said: "We are fully committed to safeguarding children and are looking into the circumstances of this case to understand how it was handled."
Parents were furious over the incident – with the Mirror reporting that some students were pulled out of school as a result of the man's presence in the classroom.
One mother said: "The question is, how didn't the Home Office or the teachers see what was blindingly obvious to everyone else?
"Heads need to roll and us parents won't rest until we get a full explanation of what went wrong."
Students reportedly discovered photographs on Facebook where he appeared to have a beard and drink beer.
The man, who is believed to be from Iran, was suspended from the school and could be deported as he is now being processed as an adult asylum seeker.
In 2016, 580 child asylum seekers – of a total 9,800 applications – had their status challenged by the Home Office. In 61% of those 580 cases, it was decided that the child was over 18.
If there is a doubt about someone's age as part of an immigration case, the Home Office can arrange for social workers to undertake an age assessment.
The claimant must be treated as an adult if their physical appearance and demeanour "very strongly suggests that they are significantly over 18 years of age".
Assessments of physical appearance can include indicators of age such as height, build, facial hair and voice pitch when there is no reliable documentary evidence to support their claimed age.
The age of teenage asylum seekers became an issue of national scrutiny in 2016 when unaccompanied child migrants were admitted to the UK.
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MP David Davies tweeted photographs of them saying "these don't look like 'children' to me".
Groups working with child migrants say child asylum seekers are left traumatised by invasive age checks built on a culture of disbelief toward those claiming sanctuary in the UK.