Britain's prison system is holding a record 273 individuals convicted of terrorism-related offenses, with the majority categorized as either Islamic or right-wing extremists. This figure represents a seven-person increase from the previous year and more than doubles the number recorded when data collection began in 2010.
According to Home Office figures, 159 inmates, or 58 percent, hold Islamist-extremist views. Another 80 prisoners, making up 29 percent, have extreme right-wing beliefs. The remaining 12 percent, or 34 individuals, are classified under 'other' ideologies, including left-wing extremism.
The total number of incarcerated terrorists has surpassed the previous peak of 267 recorded at the end of 2025. Of the 273 offenders, 165, or 60 percent, self-declared as Muslim, while 54, or 20 percent, identified as Christian. Thirty-six inmates reported having no religion.
The vast majority of these offenders, 219 individuals or 80 percent, self-declared as being from the UK. Among foreign nationals, eight are of Iraqi nationality, and five are Iranian.
Recent convictions include Vitor Dias, a 21-year-old neo-Nazi jailed for three years for collecting terrorist manuals and downloading material related to making a sub-machine gun. Adam Mahmood, 20, received a four-year sentence for possessing a terrorism video on bomb-making, among other propaganda material found on his phone.
Notable long-serving inmates include Hashem Abedi, brother of the Manchester Arena suicide bomber Salman Abedi, and Ahmed Hassan, the perpetrator of the Parsons Green bombing.
Last year, 41 convicted terrorists were released from prison. Unlike other inmates, terrorists are not subject to government plans for early release to alleviate prison overcrowding and must serve two-thirds of their sentence before being eligible for parole, subject to approval.
The figures also coincide with a rise in terror arrests, particularly following the proscription of the group Palestine Action in July of the previous year. In the year to March, 3,061 arrests were made for suspected terrorist activity, with 2,819 linked to support for Palestine Action after it was banned. The group's co-founder challenged the ban, with initial High Court rulings deeming it unlawful. However, this decision was overturned in the Court of Appeal, which found the ban to be a 'justified and proportionate' restriction on freedom of expression.