Video report by ITV News' Juliet Bremner
A British suicide bomber who helped Islamic State militants advance into the Iraqi city of Ramadi was a popular body-building schoolboy when in the UK, ITV News can reveal.
Known as Abu Musa al-Britani, A-Level student Fatlum Shakalu, 20, was among the first of six militants to blow himself up as IS surged into Ramadi.
It comes after his brother Flamur, 23, died on the frontline in Iraq in March.
One of Shakalu's former school friends told ITV News that Shakalu was an "extremely friendly" young man who liked to post pictures of his "honed physique" on social media.
His transition into extreme Islamism was gradual, the friend said, whereas his brother's conversion was far more noticeable and dramatic.
He said he believed there was a gang of around a dozen Islamic State recruiters operating in and around Holland Park School in London, where both brothers attended, targeting people they believed could be converted to their cause.
Other known jihadis Hamza Parvez and Mohammed Nasser, who died fighting in 2013, were also former students of the school.
Shakalu and his brother came from a non-devout Muslim family of Kosovan-Albanian descent
They headed out to Turkey in the spring of 2013 before moving into Syria, telling their parents they were there to do aid work.
The friend told ITV News of his shock that a classmate had turned out to be a suicide bomber.