Two teenage sisters who feared being victims of female genital mutilation and forced marriage were only rescued after they contacted the Foreign Office begging for help.
The teenagers were taken out Bethnal Green academy by their mother in July 2016 — 16 months after Shamima Begum and three classmates left the same school to join the Islamic State terror group in Syria.
The two sisters were repatriated almost a year later after texting the UK Government's Forced Marriage Unit stating that their passports had been confiscated and they were being abused at their new boarding school in east Africa.
Six months after they first went missing the sisters managed to contact friends on social media, saying they were being held against their will and "enrolled at a school where they were being beaten", according to an independent report into the case.
The government did not become aware of their plight until four months after the girls first raised the alarm.
The report found: "The two sisters were removed from school by their mother and taken to [the East African country]. There they were enrolled in a school where they were to be de-westernised.
"Despite the sisters' contact with their friends informing them of being physically abused it was not until they expressed concerns in relation to female genital mutilation and forced marriage to the Foreign and Commonwealth Office that their concerns were acted upon."
The report by Waltham Forest Council, where the family was housed by Tower Hamlets, found several occasions where "correct processes were not followed" by their UK school and the sisters' disappearance could potentially have been discovered earlier.
Their mother had gone into the school a month before they vanished to request term-time leave and was given a form to fill in. But there is no evidence this was completed and staff did not ask where the girls would be taken.
The sisters' school was the subject of media scrutiny in February 2015 after 15-year-old Begum, along with Kadiza Sultana and Amira Abase, left the UK to join Islamic State.
They followed classmate Sharmeena Begum, who had joined the group three months earlier. Following the press attention the school changed its name from Bethnal Green to Green Spring Academy.
When the sister disappeared Tower Hamlets Council's welfare adviser, who would have followed up with the family over the school holidays, was not informed of their absences.
"This was not in the girls' best interest and left [them] at risk of possible harm with no- one knowing of their whereabouts or welfare," the report states.
Three months after the sisters left, academy staff told family members still in the UK the girls risked being removed from the school roll.
Their older sister informed the school where they were but no return date or address was given and there was no visit to their home.
Allegations that the girls were being abused, made via social media, were reported to Waltham Forest Council and police but not followed up with urgency. The sisters being abroad "seems to have affected the way [the council] responded to this referral in terms of the alleged physical abuse", investigators found.
Two weeks later a housing officer also raised concerns, saying she thought that the children "might have left the country under duress".
But no further action was taken. There were also occasions when information was not shared between agencies that would have suggested they were at risk in an African country where an estimated 97 per cent of young women are subjected to genital mutilation.
This included police records that another girl in the family had been subject to an FGM and Forced Marriage Protection Order in 2009.
But it was only when the sisters contacted the government themselves that their brother was sent to rescue them in a joint operation between police, Waltham Forest and the Foreign Office.
They were taken into protective custody and a judge commended the work by Waltham Forest children's services.
It was found the girls had been put in a boarding school set up "to reverse the impact of Westernisation" but had not been subjected to FGM.
The facility has since been shut and the headmaster charged with child abuse offences.
The girls' UK school was taken over by the Mulberry Schools Trust last year and a new management team has "identified previous shortcomings".
A Tower Hamlets spokesman said: "The school has worked co-operatively with the council and has undertaken a thorough review of its policy on taking leave during term time."
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