In his former life, Abu Rafiq, a short, stocky 35-year-old who was born and raised in Damascus, ran a successful business selling groceries across Syria. Now he heads to work equipped with a camera phone. He walks the streets of Raqqa, the Syrian city that has become the self-styled capital of Islamic State of Iraq and the Levant (Isil) taking clandestine photographs and videos of anything that exposes the terrorists’ lies: bombed-out buildings, empty food stalls, homeless families. He then uploads the images to Twitter.

The clicks of a camera phone in the Levant may seemingly have little to do with what David Cameron last week called “the struggle of our generation” in his speech on Britain’s new counter-extremism strategy, but Abu Rafiq is working on its front line. Raqqa is the heart of an Isil propaganda machine so vast and sophisticated it can seep into vulnerable young minds thousands of miles away. Some 5,000 European jihadists have fallen for its message, at least 700 of whom are British. In the past three years, the Metropolitan Police has removed nearly 60,000 pieces of terrorist online content…

“There are now people in a central base who do editing for other parts of the Islamic State so they can churn these things out very quickly,” said Richard Barrett, a former counter-terrorism chief at both MI5 and MI6 and now senior vice-president at The Soufan Group, a security consultancy. He cites the appallingly stylised video of the mass murder of 21 Coptic Christians on a beach in Libya earlier this year – when the victims were marched along the sand in orange jumpsuits before being beheaded so the sea ran red with blood – as bearing all the hallmarks of Isil films made in Raqqa…