Islington prisoners are being subjected to “inhumane living conditions” as a result of overcrowding.

The warning comes from independent monitors of the conditions at HMP Pentonville in Caledonian Road.

The Independent Monitoring Board (IMB) of the men’s prison has written to Justice Secretary Dominic Raab to raise its concerns.

The letter, seen by Islington Gazette and dated December 12, sets out the challenges faced by the Victorian prison “as a result of being forced to squeeze more and more prisoners into squalid and decrepit accommodation”.

The current operational capacity of the prison is currently set at 1,155 prisoners, with plans for this to rise to 1,205 prisoners. This would represent an increase of 20 per cent in the prison population since March 2022.

Pentonville was designed in 1842 to hold 520 prisoners.

The letter also highlights the poor state of the windows and grilles in the prison. A programme of repair and replacement is currently under way, but the work is not scheduled to finish until 2030.

In the letter, Alice Gotto, chair of IMB Pentonville, says: “We are very concerned at the continued increase in prisoner numbers at Pentonville given that there has been no commensurate improvement in either the physical state of the prison or in staffing levels.

“These are consistently too low for the prison to be able to run a full regime for the prisoners and necessitate frequent lockdowns.

“In addition to the inhumane living conditions at Pentonville, the effect of overcrowding on almost every other aspect of a prisoner’s existence is hard to overestimate and in the board’s view the resulting environment is not conducive to any kind of rehabilitation.”

She adds that both the IMB’s annual report 2021-22, and His Majesty's Inspectorate of Prisons’ (HMIP’s) inspection report published in October 2022 highlighted similar concerns.

A Prison Service spokesperson said: “HMP Pentonville’s operational capacity is increasing thanks to major refurbishment and maintenance work. Capacity limits are set by the prison’s management, who assess the number of prisoners who can safely be held there.

"We are delivering 20,000 new prison places over the next few years.”

They added that the prisons minister, Damian Hinds, would be responding to the letter in due course.