History:
The early asylums were designed for largely custodial care where security and observation were the key requirements. These ideas were articulated by Jeremy Bentham who articulated in 1791 the idea of the 'panoptican' plan consisting of wings arranged around a central core from which to observe the staff and patients who were specifically segregated by gender, class and medical condition. The plans were intended for both prison and asylum design in which there was a need to supervise a large number of inmates with relatively few trained staff. Variations on this theme were designed and built that including some notable radiating and radial plans.
More enlightened approaches for a more humane treatment and environment however were articulated by William and Samuel Tuke and John Conolly. In 1842 The Lunatic Asylums Act and the Consolidating Act of 1845 made compulsory the provision of asylums for pauper lunatics and instituted regular inspections to all such establishments. By the mid 19th century the corridor plan had become popular.

Architecture:
Colney Hatch Asylum ( sometimes known as Friern Barnet Hospital) was one of the most renowned. John Conolly, the Medical Superintendent wrote:
'Among the various forms of asylums adopted, I believe there is none so convenient as the one in which the main part of the building is one line… a building of this shape, long and narrow, consisting of a succession of galleries or corridors, with bedrooms on one side only, may be moderately perflated by every wind that blows- anm advantage extremely salutary to those who pass their whole time in it.'
The long corridor measured about a quarter of a mile and it provided a separate circulation route for staff from patients. Designed in 1848 by S W Daukes it was originally intended for some 300- 400 patients. Conolly made recommendations about the size of the galleries, number of single rooms and dormitories. The asylum was planned in extensive grounds and many were virtually self sufficient communities with farms, water towers and recreational facilities.
The Care in the Community Programme that developed from the 1950s called for the closure of the mental asylums in the UK. Most, if not all, have now been closed with new facilities being developed in more community settings. Like many others, Coloney Hatch has been converted into luxury residential accommodation. The landscaped grounds have been developed to provide further residential accommodation.