Shamima Begum was a London schoolgirl until Scotland Yard raised concerns she and two of her fellow pupils had travelled to Syria in February 2015.

The now 23-year-old was just 15 when she travelled to Istanbul in Turkey from Gatwick Airport to join the so-called Islamic State (IS) with her close friends at Bethnal Green Academy – Kadiza Sultana, 16, and Amira Abase, 15.

Despite her family’s warnings that Syria was a “dangerous place”, the then teenager, described as a “straight A student”, crossed the border just days later with the help of a Canadian spy named Mohammed Al Rasheed, according to reports.

In the Shamima Begum Story BBC podcast series, she said she was told to “pack nice clothes so you can dress nicely for your husband”.

Just 10 days after arriving in the city of Raqqa, Ms Begum, who is of Bangladeshi heritage, was married to a Dutchman named Yago Riedijk, who had converted to Islam.

They had three children together, who all later died from malnourishment or disease. They were a one-year-old girl, a three-month-old boy and newborn son.

Ms Begum left Raqqa with her husband in January 2017, but they were eventually split up, as she claimed he was arrested for spying and tortured.

She was eventually found nine months pregnant in a refugee camp in al-Roj in February 2019 by a Times journalist.

Ms Begum told the reporter it “didn’t faze me at all” when she saw her first “severed head”, but would “do anything required just to be able to come home”.

But the runaway schoolgirl said she did not regret travelling to IS-controlled Syria, saying she had a “good time”.

The then-Metropolitan Police commissioner Dame Cressida Dick said Ms Begum could expect to be “spoken to” if she returned to the UK.

In the same month, she was stripped of her British citizenship after announcing her desire to return to the UK with her then unborn third child.

The move was deemed only permissible under international law if it did not leave her stateless.

Since then, the former IS bride has been embroiled in a battle with the British legal system – she lost her latest legal challenge over the decision to deprive her of her British citizenship on Wednesday.

Ms Begum described the initial move to revoke her citizenship as “unjust on me and my son”.

The then-home secretary Sajid Javid said although he would never leave an individual stateless, his priority was the “safety and security” of the UK.

Mr Javid was criticised by Labour after Ms Begum’s son later died – with the then-shadow home secretary Diane Abbott describing the situation as “callous and inhumane”.

She lost her first appeal to return to the UK but successfully challenged the decision at the Court of Appeal.

But the Government submitted a fresh appeal, meaning her return was put on hold pending a Supreme Court battle.

She was dealt a fresh blow when the Supreme Court ruled she could not come back to the UK – leading to her begging the British public for forgiveness.

When she appeared on TV screens in September 2021, she had drastically changed her appearance – wearing a Nike baseball cap, a grey vest, Casio watch and with her fingernails painted pink.

Ms Begum said there was “no evidence” she was a key player in preparing terrorist acts and was prepared to prove her innocence in court.

She denied her Western physical appearance on Good Morning Britain – in stark contrast to the traditional Islamic dress she previously adorned – was a publicity stunt.

In the BBC podcast series released last month, she said she understood public anger towards her, but insisted she is not a “bad person”.

She told the podcast she accepted she is viewed “as a danger, as a risk”, but blamed her portrayal in the media.

Floodgates could be opened for Islamic State supporters coming back to the UK if Shamima Begum succeeds in getting back into the country, a former counter-terrorism police chief has warned.

Scott Wilson, who helped lead the response to the 2017 London Bridge attack, said monitoring the teenager would cost millions of pounds and the security services and police would “never be able to take their eye off her” if she did return.

Begum, who left her east London home to join IS in Syria in 2015, wants to return to the UK for the sake of her newborn third child, but has been stripped of her British citizenship.

Home Secretary Sajid Javid made the move on advice that she qualified for Bangladeshi citizenship through her mother, although authorities there have said they will not let her enter the country.

Mr Wilson, who was UK National Counter Terrorism Co-ordinator for Protect and Prepare until last summer, said: “When you look at all the background to her going out there, I know they are trying to say she was a groomed child, but there was a lot of planning that went in with her and her group to get herself out there.

“It’s not just the bringing her back, the deradicalisation programme; the security services will end up spending years monitoring her.

“They will never be able to take their eye off her for the simple reason that they don’t know what could happen. If she did do something in the UK, the Government and the security services would get the blame for it.

“It’s the millions of pounds of monitoring that it’s going to cause, not just the bringing her back and putting her through a deradicalisation programme.”

Last week, Oxford-born terror suspect Jack Letts, known as Jihadi Jack, said he wants to return to the UK, and misses his mother, pasties and Doctor Who.

It was also reported that Abu Hamza’s son, Sufyan Mustafa, 23, is fighting the decision to revoke his British passport.

Mr Wilson believes a slew of suspected IS supporters will want to return to the UK if Begum succeeds in doing so.

“I don’t think the British Government should give her the way to get her out of Syria and get her back here, that’s the point,” he said. “If she gets back here then it’s on their plate to deal with it.

“If you start making a free way for them to get back then where do you stop?

“I can see floodgates opening. I don’t think we should make it easy. If you make it easy then you’re just opening the floodgates for it and suddenly you’re monitoring people forever.

“I don’t sound very sympathetic because I just see the consequences. I dealt with London Bridge on the streets.

“When you see the consequences of this, I just think this country can be too sympathetic at times. She made the decision so she will have to stick to the decision she made.”

Begum’s father, Ahmed Ali, said his 19-year-old daughter should face justice in Britain despite previously appearing to back the removal of her citizenship.

The teenager, who married Dutch IS fighter Yago Riedijk, had two older children who both died.

Mr Ali told ITV News: “I don’t think he’s (Sajid Javid) done the right thing because she is a British citizen, and if it turns out she has committed any crimes, then she should face justice in the UK.

“She belongs to this country, she belongs to England.

“My daughter was a little child, she made a mistake, she didn’t properly understand.”