'Jihadi Jack' says he hates IS more than Americans
Jack Letts, dubbed "Jihadi Jack", travelled to IS-occupied Syria in 2014, shortly after the group announced their self-declared "caliphate" in the territories they controlled in Syria and Iraq.
He told the BBC that he got married and had a child in Iraq, before being arrested by the jihadi group.
Letts said he became dissatisfied with life in IS territory and claims he became a thorn in the side of the group after witnessing their "un-Islamic" practices.
"I hate them more than the Americans hate them," he said.
"I realised they were not upon the truth so they put me in prison three times and threatened to kill me."
Letts told the BBC that he grew disillusioned after seeing the militants murder supporters and decided to risk his life and escape.
This happened after he was taken to recover in Raqqa after being injured in a bomb blast although he claims he never fought with the group.
Letts dropped out of 'A' Levels and left his Oxford home for Jordan aged 18, before leaving for the IS territory months later in Autumn 2014.
He arrived at a time IS expansion in Syria and Iraq seemed unstoppable, capturing swathes of territory from the Baghdad government and Syrian rebels.
In June 2014, IS announced a "caliphate" with Abu Bakr al-Baghdadi declaring himself "Caliph Ibrahim" during his only public appearance at Mosul's Grand al-Nuri Mosque drawing condemnation from moderate Muslims and other jihadi groups.
Later, Letts said he found a smuggler to help him escape the territory.
"I found a smuggler and walked behind him through minefields," he told the BBC.
"[We] eventually made it near a Kurdish point where we were shot at twice and slept in a field."
Letts is being held in solitary confinement by a Kurdish militia and said he was motivated by humanitarian impulse rather than a desire to fight.
The 21-year-old said he "doesn't want anyone to help" him, while his family said he will after "account for his actions" once he returns to the UK.
"I'll just chill here in solitary confinement 'til someone decides it's easier to kill me," Letts told the BBC.
Around 850 British people went to Syria and Iraq to support or fight for jihadi groups, with most believed to have joined IS.