UK government has no idea how many British jihadis are still in Syria, despite some of the most dangerous fanatics who left to join ISIS being among them

The government does not know how many Britons who left to fight for Islamic State ten years ago remain in Syria today, it has been revealed.

A quarter of some 900 British citizens who have left to the region since 2013 are still yet to return, according to the Home Office.

More than 200 of them are whereabouts unknown. A 2018 report referencing persons of ‘national security concern’ claimed 20 per cent had been killed overseas and 40 per cent had returned to the UK.

Maya Foa, executive director…