Islamic preacher Anjem Choudary is facing jail after he was convicted at the Old Bailey of drumming up support for the “Islamic State” along with co-defendant Mohammed Mizanur Rahman.

Choudary, 49, has been found guilty at the Old Bailey along with Rahman, a 33-year-old from Sidney Street in Whitechapel, of inviting support for IS between June, 2014, and the following March.

The verdicts were delivered on July 28, but for legal reasons could only be reported for the first time today.

Choudary had encouraged backing in a series of talks posted on YouTube. He recognised a caliphate—a symbolic “Islamic state”—which has been created by the terrorist organisation after it was proclaimed on June 29, 2014, the court heard.

He was a leader figure in the banned extremist group al-Muhajiroun with its former supporters later convicted of terrorism—but stayed on “the right side of the law” for 20 years before investigators were able to pin him down.

The judge warned both Choudary and Rahman who had only shown “a grudging compliance” to the court that they face prison. Choudary faces a possible maximum of 10 years.

Mr Justice Holroyde admitted: “There is very little in the way of precedent in sentencing.”

Police pounced after Choudary and three others lent their names to an “oath of allegiance” to IS which was posted on the internet.

The notorious preacher—a key force in radicalising young Muslims—had been the mouthpiece of Omar Bakri Mohammed, founder of the banned al-Muhajiroun organisation, the trial heard.

He courted publicity by voicing controversial views on Sharia law, while building up a following of thousands through social media, demos and lectures around the world.

Choudary set out his ambitions for the Muslim faith to “dominate the whole world” in one speech in March, 2013.

His supporters included Michael Adebolajo and Michael Adebowale—the murderers of soldier Lee Rigby at Woolwich in 2013—and suspected IS executioner Siddhartha Dhar.

He consulted his “spiritual guide” Omar Bakri Mohammed, currently in jail in Lebanon, and Mohammed Fachry, head of al-Muhajiroun in Indonesia, before accepting “the caliphate” was legitimate.

Rahman’s name appeared on the oath alongside theirs on July 7, 2014, which stated the Muhajiroun had “affirmed” the legitimacy of the “proclaimed Islamic Caliphate State”.

The defendants followed up by posting a series of lectures on the caliphate on YouTube, which Choudary promoted to 32,000 Twitter followers.

Choudary denied encouraging his followers to back al-Muhajiroun and claimed the oath had been made without his knowledge.

Yet he continued to express extreme views during his Old Bailey trial—despite protesting his innocence—and refused to denounce the execution of journalist James Foley by Mohammed Emwazi, known as “Jihadi John”, in Syria in 2014.

He told the jury: “If you took an objective view, there are circumstances where someone could be punished.”

Rahman and preacher Choudary are both being sentenced on September 6.