In Victorian-era prisons, deteriorating and fragile walls are obstructing efforts to prevent drones from delivering illicit substances and weapons to inmates.
According to prison governors, initiatives to implement robust netting and reinforced window grilles aimed at blocking drone access have been hindered due to the walls’ inability to support the additional load.
Sources indicate that recent efforts to install anti-drone measures at HMP Pentonville, a historic prison located in north London, encountered difficulties when it became apparent that the bricks were too soft to accommodate the necessary infrastructure.
Charlie Taylor, the chief inspector of prisons in England and Wales, remarked last month that the Prison Service has effectively lost control of the airspace above many facilities to organized crime, posing a significant threat to national security.
Data shows that incidents involving drones in prisons have surged by over 1,000% in the past four years, with gang members managing to fly packages directly to cell windows, which inmates retrieve using hooks.
The prevalence of drone usage has increased to such an extent that inspectors have discovered packages exceeding 15 kilograms, containing items like weight loss medications, hair loss treatments, anabolic steroids, and fast food.
To combat this, nets can be installed on walls to entangle drone propellers, while fixed grilles on windows can prevent inmates from pulling in these packages.
However, Tom Wheatley, president of the Prison Governors Association, expressed concerns that anti-drone measures are not being implemented swiftly enough and face structural challenges.
“Physical barriers such as netting, wires, and grilles are the most effective methods for preventing contraband from entering prisons, making it nearly impossible,” Wheatley stated. “In some facilities, there are worries that these installations may add excessive weight to the walls, potentially compromising the integrity of the structures.”
HMP Pentonville, categorized as a category B prison housing around 1,200 inmates, is currently undergoing a major renovation following an urgent notification issued by Taylor in July. While some netting was previously installed in the exercise yard, plans to implement stronger mesh in other areas were halted after engineers determined the walls could not withstand the necessary tension.
An industry expert attributed the challenges to the softness of the ‘London stock brick’ used in the prison’s construction in 1842. “The yellowish bricks are not only soft, but the mortar is also quite old, complicating the installation of ropes and meshes,” the insider explained. “To address the issue, one must design steel brackets and supports that distribute the load, which becomes challenging in confined spaces. It’s a complex problem.”
The recorded number of drone incidents in prisons rose dramatically from 138 incidents in the year ending March 2021 to 1,712 incidents in the year ending March 2025, not accounting for undetected drone drops.
A gang that utilized drones to smuggle drugs into Pentonville and other London facilities was sentenced to prison in March.
Government officials aim to expand the deployment of anti-drone netting in correctional facilities. Justice Secretary David Lammy even visited the Ukrainian military in January to explore how battlefield strategies could be adapted to counter drone usage in prisons.
In 2024, inspectors called for a comprehensive review of security measures in Victorian prisons after it was discovered that inmates at HMP Winchester had managed to tunnel through cell walls using plastic cutlery.
The government has pledged £10 million towards enhancing anti-drone initiatives. A spokesperson for the Prison Service refuted claims that certain prison walls were too weak to support anti-drone systems, stating, “All enhancements to prison security are customized for each facility following thorough structural evaluations to ensure their safety and effectiveness.” They also noted, “We have invested more than £40 million in various physical security upgrades. These improvements will enhance safety, reduce drone activity, and target suspected misconduct within the facilities.”
