In the weeks after Isis took control of the Raqqa province, northeast of Syria, and then rampaged through Iraq, a hazy picture of this ultra-barbaric group began to emerge. We soon knew of their penchant for hanging bodies in their street, and that several foreign fighters, including Britons, have joined them.

Yet, in those early weeks and months, people couldn't really get behind Isis, get a clear picture of who they are and what they are fighting for. Sure everyone could see the headless bodies and the teens on tanks, but no-one could get the high-definition close-up they longed for.

Now, after speaking to my contacts in Raqqa and drawing on my own experience of living in the city under Isis rule, I can offer a detailed view of this terrifying and enigmatic group - and shine a light on the women, children, and British fighters at their core.

Child soldiers and female vigilantes

It is well known that the "Islamic State" recruits a large number of children under the age of 18 who do not have any form of religious extremism. In fact, there are people in the organisation whose task it is to recruit children by brainwashing or by offering large sums of money; they also have dedicated camps for ideological training and a "religious" military service.

Also, in Raqqa there is a battalion consisting of more than 50 women affiliated to Isis called the "Al-Khansa Battalion", whose job it is to patrol the streets to pursue women. These women are the wives of immigrants to Syria, who are from a number of different nationalities but mainly Tunisian, Moroccan, French, and British.

Not too long ago the Al-Khansa battalion patrolled the city's schools shortly before they were closed down by the Islamic State and introduced legal marriage, as they call it, to the Mujahidin which was met with big disapproval from the city's people and the families of the female students, prompting many of them to leave the city and not to send their daughters to schools, and even leave the house.

'We left Britain because you can't practice religion there'

There are people from many nationalities in the Islamic State, including several groups from Western Europe, who live in Raqqa with as much luxury as Isis can provide them. They get their homes for free, as well as flashy cars and huge salaries, while the people of the city of Raqqa suffer from not having a living wage because most of them are employed in public or state institutions or live off agriculture, which has now almost been discontinued due to the high cost of raw materials.

Abu Hammam, one of the activists who works inside the city secretly, said that he saw several European people, whom he could tell were British from the manner in which they spoke, wandering inside the city. One of the Britons, he says, was called Abu Abdullah.

Upon seeing them, Abu Hammam said "I have a question: why did you all come to Raqqa?" They replied saying that in Britain you cannot (truly) practice your religious rites, while acknowledging that the British government doesn't infringe on the freedom of religion and religious rites. They said they came here after the announcement of the Islamic State organisation to establish a Caliphate based on the method exemplified by the prophet Mohammed.

The Britons added that they were assured of this after their leader, Abu Bakr al-Baghdadi, announced the establishment of a true Islamic Caliphate; they also came to fight the Nusayri "infidels" – as Abu Hammam calls them.

Osama bin Laden Cub Camps

Abu Hammam also revealed that the presence of people of different nationalities is severely straining the demographic situation of the city and that the Islamic State began the process of demographic change in Raqqa after they deported all other non-Sunni Muslim sects. He said that this matter is very serious and that the organisation poses a major threat to the Syrian society in general and Raqqa in particular.

This threat is most acute among children under the age of 18, as the Islamic State has started to prepare "shariah camps", including one named the "Osama bin Laden Cub Camp" in the eastern countryside of Raqqa, and another named "Camp Al-Zarqawi" in the rural north. In these camps, there is brainwashing, military training and psychological preparation for the making of suicide bombers to carry out suicide operations for them.

This is considered a danger for the distant future; even if the Islamic State does leave Raqqa, the danger that its men, women and children will leave behind could haunt us for 10 years.