Aine Davis, 38, is remanded in custody in the UK after being deported from Turkey.
A man alleged to be a member of an IS terror cell nicknamed The Beatles has been charged with terrorism offences.
Aine Davis, who denies being part of the group, has been remanded in police custody and is due to appear at Westminster Magistrates’ Court later.
He was arrested at Luton Airport, Bedfordshire, after being deported to England by Turkey on Wednesday.
The 38-year-old is charged with possession of a firearm for a purpose connected with terrorism.
He was charged with offences contrary to sections 15, 17 and 57 of the Terrorism Act of 2000 following an investigation by the Metropolitan Police’s Counter Terrorism Command.
The CPS had authorised the Metropolitan Police to charge Mr Davis for terrorism offences in 2014.
He has spent more than six years in a Turkish prison.
He is alleged to be the fourth member of the IS gang that tortured and murdered western hostages in Iraq and Syria, which he denies.
The ringleader of that gang, Mohammed Emwazi, was killed in a US drone strike seven years ago.
Two others were captured in Syria, and taken to the US, where both have been convicted of committing some of the most gruesome crimes in recent history.
The terror cell was nicknamed The Beatles after the Liverpudlian band, due to the members’ English accents.