The mosque rose to notoriety after Abu Hamza al-Masri became its imam in 1997.
In the late 1990s and early 2000s, he consolidated his control of the mosque, with his followers preventing anyone they did not trust from entering it.
According to the mosque's current administration, although originally appointed by the trustees, Abu Hamza gradually took over the mosque from them.
When the mosque's trustees asked him to leave, they allege that he resorted to intimidation.
In October 1998, the trustees went to the High Court to stop Abu Hamza from preaching at the mosque.
They were granted an injunction, but it was not enforced.
Many trustees reported being barred from their own mosque by Abu Hamza's supporters and even being assaulted.
In April 2002, the Charity Commission for England and Wales suspended Abu Hamza from preaching, but he continued anyway.
 Djamal Beghal used the mosque as his "base," as he planned a foiled 2001 suicide bombing of the American Embassy in Paris.

During Abu Hamza's control, the mosque's attendance dropped.
Most of the attendees were his followers.
The mosque also became a meeting point for many radical Muslims.
According to classified American documents released by WikiLeaks, Finsbury Park mosque previously served "as a haven" for Islamic extremists who subsequently fought against allied forces in Afghanistan.
Al Qaeda operatives including "shoebomber" Richard Reid and Zacarias Moussaoui attended the mosque.
In 2002, The Guardian reported that weapons training had taken place inside the building.
On 11 September 2002, a conference was held at the mosque titled "A Towering Day in History" to praise the September 11 hijackers on the anniversary of the attack with the participation of Anjem Choudary, Abu Hamza, Omar Bakri Mohammed, Mohammad al-Massari and others.
In the late 1990s, Abu Hamza and the mosque became the leading international spiritual reference supporting the Armed Islamic Group of Algeria (GIA) in the Algerian Civil War, at a time when the GIA was spurned even by most Salafi-jihadist groups for their massacres of civilians.

The United States charged Abu Hamza as a "terrorist facilitator with a global reach" in 2004; he was arrested, sentenced in the UK to a seven-year prison sentence in 2006, and subsequently extradited to the United States where he was sentenced to life in prison without the possibility of parole.
According to disclosures via WikiLeaks, several Guantanamo Bay detention camp detainees passed through the mosque prior to their subsequent activities.

The mosque's role in facilitating terror operations during these years is often mentioned in the context of the Londonistan, which was widely used by the international espionage community to describe London, due to the liberty afforded to Muslim extremists by British authorities.
The mosque rose to notoriety after Abu Hamza al-Masri became its imam in 1997. In the late 1990s and early 2000s, he consolidated his control of the mosque, with his followers preventing anyone they did not trust from entering it. According to the mosque's current administration, although originally appointed by the trustees, Abu Hamza gradually took over the mosque from them. When the mosque's trustees asked him to leave, they allege that he resorted to intimidation. In October 1998, the trustees went to the High Court to stop Abu Hamza from preaching at the mosque. They were granted an injunction, but it was not enforced. Many trustees reported being barred from their own mosque by Abu Hamza's supporters and even being assaulted. In April 2002, the Charity Commission for England and Wales suspended Abu Hamza from preaching, but he continued anyway.  Djamal Beghal used the mosque as his "base," as he planned a foiled 2001 suicide bombing of the American Embassy in Paris.
During Abu Hamza's control, the mosque's attendance dropped. Most of the attendees were his followers. The mosque also became a meeting point for many radical Muslims. According to classified American documents released by WikiLeaks, Finsbury Park mosque previously served "as a haven" for Islamic extremists who subsequently fought against allied forces in Afghanistan. Al Qaeda operatives including "shoebomber" Richard Reid and Zacarias Moussaoui attended the mosque. In 2002, The Guardian reported that weapons training had taken place inside the building. On 11 September 2002, a conference was held at the mosque titled "A Towering Day in History" to praise the September 11 hijackers on the anniversary of the attack with the participation of Anjem Choudary, Abu Hamza, Omar Bakri Mohammed, Mohammad al-Massari and others. In the late 1990s, Abu Hamza and the mosque became the leading international spiritual reference supporting the Armed Islamic Group of Algeria (GIA) in the Algerian Civil War, at a time when the GIA was spurned even by most Salafi-jihadist groups for their massacres of civilians.
The United States charged Abu Hamza as a "terrorist facilitator with a global reach" in 2004; he was arrested, sentenced in the UK to a seven-year prison sentence in 2006, and subsequently extradited to the United States where he was sentenced to life in prison without the possibility of parole. According to disclosures via WikiLeaks, several Guantanamo Bay detention camp detainees passed through the mosque prior to their subsequent activities.
The mosque's role in facilitating terror operations during these years is often mentioned in the context of the Londonistan, which was widely used by the international espionage community to describe London, due to the liberty afforded to Muslim extremists by British authorities.
Finsbury Park Mosque