The Supreme Court's blocking of Shamima Begum coming back to the UK is a huge victory for two successive Home Secretaries but will consign her to years of incarceration in a Syrian detention camp.

This has come as a massive surprise to the UK security community.

Sources have told the Mirror, police and MI5 had already made plans for her return, predicting the decision would go against the Home Office.

The court made it clear this is not the end for Shamima.

But she will have to appeal from where she is or if her circumstances change, making her return in the near future highly unlikely.

The case was immensely complex, even without the obvious emotional reaction to a young girl being seduced into joining ISIS.

Shamima Begum speaks to a reporter
Shamima Begum is being held at a detention camp in Syria

Her legal team had successfully argued she could not feasibly launch her case from a tent in a Syrian camp and had to return to the UK so she could make her case.

Many in the counter-terrorism community feared the Supreme Court would rule in her favour, paving the way for many British jihadis to return.

It would have meant she would likely face a parallel case for having been a member of Islamic State – and her staying in the UK.

Shamima Begum is seen at security at Gatwick before flying to Turkey
Begum, then 15, is seein at Gatwick Airport before flying to Turkey in 2015
Shamima Begum sits inside a tent at a detention camp in Syria
The ISIS bride wants to return to the UK to pursue her citizenship appeal

The legal debate on Shamima's return was messy and looked into whether legally she could be denied access to the UK and whether her appeal against the Home Office was legally sound.

However, outside of the courts system, the Shamima Begum debate is clear cut.

As far as British people should care, she would either have been a danger to them or not – and the Home Office has always said she presents a serious terror risk.

There is no doubt she could have been a danger once back in the UK as ISIS was extremely skilled at teaching its followers how to hide their radicalised intent if caught.

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Even if she did nothing obvious she could have acted as a jihadist figurehead.

The Shamima Begum debate will rage for years.

Daily Mirror teams have seen many times in interviews with British ISIS prisoners in Syria – all of whom claim they did nothing wrong, never held a gun, etc etc.

And what could be more convincing than a desperate child bride, seduced aged 15 into the world's most feared terror group, who has lost three children and is left to rot in Syria?

She may be very convincing.

But had she been allowed to return she would have had to be watched intensely by counter police and MI5, costing the UK millions.