HMP Millsike is built on a site near Full Sutton, North Yorkshire, and was completed by the Kier Group in March 2025, with the first prisoners arriving the following month. It is the UK’s first all-electric prison, powered by solar panels and heat pumps rather than gas, and is estimated to use significantly less energy than older prisons. Construction used a precast concrete “kit of parts” system, with each house block built in around 12 weeks.
Accommodation
The prison has six house blocks, though not all had opened at the time of writing; by the end of 2025 four were in use. Design capacity is around 1,500 places, with the population being built up gradually as further house blocks come into use. Cells feature bar-less, drone-resistant windows and extensive CCTV coverage.