Britain's newest prison experienced a "chaotic atmosphere" in its first18months, a former worker told a BBC investigation. HMP Millsike, in East Yorkshire, was praised by authorities for setting “the standard for the future” when it opened in March 2025 with 1.500 places. However, former workers described staff shortages, inadequate training, and often saw specialist officers called in to deal with serious incidents.

Illustration. Mitie, the company that manages category C prisons, said safety was its "highest priority" and was "operating in accordance with plans agreed with the Ministry of Justice". Shabana Mahmood (left), then Minister Justice, on a prison tour with director Samantha Pariser in March 2025.

Pariser was replaced in February this year

Millsike was built with a focus on rehabilitation and education and cost around £400m. Illustration. It is the first of four new prisons to be built opened under authorities' pledge to build 14.000 places by 2031.

Around 1.100 inmates are being held there currently, according to the Ministry of Justice (MoJ). Reports of a disturbance in November 2025, with a former worker claiming that a prisoner "lost it" and the prison's elite squad had to be called in. Illustration.

Thesewage pump station broke down the same month, amid reports that inmates had been flushing clothes down the toilet, although Mitie denied this. Sentence of a female prison officer, who was given a suspended sentence of eight months in prison in June 2026 after admitting to a relationship with an inmate. The BBC spoke to seven former prison employees, including a prison officer and staff members.

All except one wished to remain anonymous, despite describing a "chaotic atmosphere" insideMillsike. Some staff expressed concerns about the experience of other staff, and claimed that some staff had a background working in supermarkets and fast food chains. The BBC understands that all operational staff have completed more than eight weeks of training, including shadow roles at other prisons.