Belgians pay tribute to the victims of the terror attacks in Brussels in March. Photograph: Nicolas Maeterlinck/AFP/Getty Images
In Belgium, which is coping with the aftermath of
terrorist attacks in March and fearing more to come, Choudary helped set up Sharia4Belgium.
According to the European law enforcement agency Europol, Sharia4Belgium engaged in organised indoctrination and recruitment of young people to participate in the armed conflict in Syria. Choudary praised its leader after more than 40 of its members were convicted of terrorism.
The groups Choudary led were the single biggest gateway to terrorism in recent British history, says one study on his activities, details of which are published here for the first time, from the leftwing group
Hope Not Hate. It said: Over the last 15 years he has influenced and inspired over 100 Britons who have carried out or attempted to carry out terrorist attacks at home and abroad.
According to research from Hope Not Hate, supported by a counter-radicalisation expert who has worked with al-Muhajiroun members, Choudary helped Isis gain British recruits.
Hope Not Hate said: In the six months following the creation of the Islamic State, Choudary was its biggest cheerleader in the English-speaking world and the network he helped create became the largest recruiter for IS in Europe.
Choudarys ability to operate in plain sight, seemingly without legal sanction, raises many questions. Sources in Britains Muslim community say Choudary was reported to the police, with some in the UKs Islamic communities left baffled about how he remained untouched for so long.
Scotland Yards counter-terrorism command had previously attempted to build criminal cases against Choudary, only to be rebuffed by the Crown Prosecution Service, which judged there was insufficient chance of gaining a conviction.
Haydon said of the conviction reported for the first time: The oath of allegiance [made by Choudary to Isis] was a turning point for the police. At last we had the evidence that they had stepped over the line and we could prove they supported Isis.
Between August and September 2014, Choudary and Rahman posted speeches on YouTube encouraging support for Isis. An audio clip, lasting one hour and six minutes and uploaded to Choudarys YouTube channel on 9 September 2014, was played to jurors. Titled How Muslims Assess the Legitimacy of the Caliphate, the speech was played over the image of a map of northern Africa, the Middle East, north-west Asia and southern Europe. Choudary begins by setting out his views about the requirements of a legitimate Islamic caliphate, then explains why he sees Islamic State as meeting the criteria. The lesson from this narration is that obedience to the caliph is an obligation, if they rule by the sharia. And to obey them obviously means they must be established, Choudary said.
Estimates of how many people Choudary funnelled into violence range from 100 to 500. Hannah Stuart, of the
Henry Jackson Society thinktank, said: A quarter of all individuals convicted of Islamism-inspired terrorism and terrorism-related offences in the UK since 1999 had direct links with al-Muhajiroun (or its aliases), through public membership, al-Muhajiroun-linked activism or regular attendance at lectures and protests. One in 10 offenders had a proven personal relationship with Choudary in particular.
British Muslims had complained about the media attention paid to Choudary and the impression given to audiences that he was representative of British Islamic thought.
Miqdaad Versi, of the Muslim Council of Britain, said: Mr Anjem Choudary has long been condemned by Muslim organisations and Muslims across the country, who consider him and his support for Daesh [Isis] to be despicable and contrary to the values of Islam and our nation.
Many Muslims have long been puzzled why this man was regularly approached by the media to give outrageous statements that inflamed Islamophobia.
One expert in counter-radicalisation said Choudary was useful for Isis in the early days, when it was looking to gain traction in the UK. But the likes of him are now needed barely at all because Isiss reputation in jihadi circles and its online machine has grown so much. They dont need a middle man, said the expert.
Choudary and Rahman will be sentenced next month and face a maximum of 10 years in prison.
The home secretary, Amber Rudd, said: The successful conviction of Anjem Choudary and Mohammed Rahman is recognition of the tireless efforts of police and security agencies to keep the people of this country safe.
These dangerous individuals were recruiting sergeants for Daesh. They poisoned the minds of vulnerable people and their warped and twisted propaganda offered support and succour to a murderous and barbaric terrorist organisation.
The government is clear. We will continue to confront those who promote hate and threaten our way of life. Together we will protect communities against extremism and defeat this toxic ideology.