H M Prison Dartmoor: former Petty Officer's Block, now Chapel, Primary Care Unit and Segregation Unit

This building, originally the Petty Officer's Block at H M Prison Dartmoor, was constructed between 1806 and 1809 as part of the prison’s initial design as a camp for Prisoners of War. Around 1850, it was converted into an infirmary, incorporating a chapel, and further altered and extended between 1909 and 1912. The interior of the chapel was remodelled around 1950.

The building is primarily constructed of granite stone rubble, with later additions in granite ashlar. It has a pitched roof now covered in metal, punctuated by tall ventilation towers at the gable ends. The original U-shaped plan has evolved since the early 20th century to a double L-shape, with the chapel forming the wing at the far north-west end and the primary care and segregation units attached to its south-east end.

The chapel, the northwestern wing, is entered via a small porch added in the late 20th century, alongside a later casement window. Inside, the nave features a blocked arcaded basement and tall, rectangular multi-pane church windows. Attached to the northeast corner is a former fire station added in 1927, featuring restored round arched fire engine doors at ground floor level and later windows replacing original multi-pane sashes at first floor. The fire station abuts the chapel’s east end, where two round arches are visible at basement level, and a tall, tripartite choir window sits above.

The central block, representing the former hospital ward from around 1850, extends from the chapel's southwest corner. The west elevation displays rows of identical square cell windows, while the east elevation exhibits an arcaded basement and two rows of narrow, rectangular cell windows above. A tall, three-story projecting ablution tower was added between 1909 and 1912. Attached to the south end of the central block is a large, three-story L-shaped wing, now housing the Primary Care and Segregation Units. While remnants of the arcaded basement survive, most of the southeastern wing dates from 1909-1912, characterized by rows of tall prison sashes. A gabled entrance on the west end of this wing bears the date stone 1912, set above an entrance lobby accessed by a small bridge crossing a landscaped ditch along the west elevation.

The chapel's interior from the 1950s remains, including the sanctuary with a coffered ceiling, stained glass windows above the altar, and hanging pendants in the nave. Timber panelling from the 1920s is preserved in the entrance lobby of the Primary Care Unit. The remainder of the building’s interior was inaccessible during a 2015 inspection.