Glasshouse, or The Glasshouse, was historically the term for a military prison in the British Army, although the expression is now seldom used within the military itself. The first military prisons were established in 1844. The term Glasshouse originated at the military prison at Aldershot, which had a glazed roof. Over time, the sobriquet came to be applied to all British Army prisons. This prison, called the Detention Barracks, had begun as several barracks in 1856, before being replaced by a single, large building, modelled on civilian prisons, in 1870. This building was destroyed by fire in a riot of 1946.
Glasshouses gained a reputation for brutality, as depicted in Allan Campbell McLean’s novel, The Glass House, and the Sean Connery film, The Hill. Today, the British Army has only one remaining prison, the Military Corrective Training Centre at Colchester. It has a special unit for convicts who are being transferred to HM Prison Service to serve their sentences, which is for anyone serving a sentence over three months.
The Glasshouse at Colchester has been described in the ITV Anglia TV-documentary series and Red Cap starring John Thaw.