Upon closure, the initial goal of the NHS was to secure the site in order to minimise vandalism in the empty buildings. This was achieved using a chain link fence with barbed wire on top, with wooden boards fixed over ground floor windows on the domestics block and the modern boiler house, which straddled the boundary road and were thus unprotected. Security guards from Securior were based within the hospital’s administration building.
Croydon Council holds a record of planning applications for various changes, the first of which was in 1986, for a petrol station and restaurant. This was refused, along with an application for “Residential development of approx 1200 housing units, together with community/health facilities, recreational facilities, public open space and accommodation for mentally handicapped”
In 1988 consent was granted for a single storey prefabricated building for use as a kitchen. It is not clear where this was sited.
In August 1991 consent was granted for a mobile power plant, which may have been in connection with the proposal to operate as a mini-institution until the Knights Hill Home was ready, or to provide power to the TV repeater on top of the water tower.
In 1993 applications to use ancillary buildings at The Postern, East Lodge and North Lodge as dwelling houses were refused. These buildings subsequently fell into dereliction with East Lodge being demolished as part of the works for the Couldson Bypass which added a new entrance to the site slightly west of the East Lodge Entrance, and the Posterns being demolished along with the majority of the hospital in 2008-09. North Lodge was advertised for sale in 2020 as a building plot and remained derelict in 2021.
In 1996 a draft development plan for the site was published, in which South Thames Health authority indicated a need for a 120 bed medium secure unit (MSU) on the site of the former Portnalls House, to expand on the existing 23-bed secure unit, which opened in 1987 and was operated by South London and Maudsley NHS Trust. In 1999, this proposal was challenged vociferously in the House of Commons by Richard Ottaway, MP for Croydon South, who described the plan as ‘messing about with the green belt’ which would be detrimental to its quality.
In 1999 an application was made to demolish the majority of the existing buildings in order to erect a science and business park, with space for retail, financial and professional services, food and drink, a hotel, a business innovation centre and leisure and social facilities. The application was not determined and the plan was abandoned. The council had been working on a plan for a science park on the site, which was described as having failed ‘due to dithering’. The matter of compatibility between a 120 bed MSU and a science park was also raised, along with local concerns about the impact of the MSU on the local community.
In response to various arson attacks around 2001, affecting the main hall, two ward blocks and a number of ancillary areas, consent was granted for a 2.7m high metal/barbed wire palisade security fence enclosing the main hospital buildings. In April 2003 this was followed with an electrically operated access gate, single storey security guard cabin, 1.8m high fencing and 2 CCTV cameras. This may have been in response to various groups purportedly parking their minibus outside the administration block in order to trespass! It also signifies the security guards’ relocation from the administration building to the site’s entrance on Brighton Road, at the aforementioned East Lodge.
In 2004, Cane Hill was sold by the NHS to English Partnerships.
In 2006, an application was made to English Heritage for the buildings to be listed, although this was rejected because ‘better examples of early echelon asylums exist’, despite Cane Hill being built to a unique and innovative radiating pavilion design that predated GT Hine’s echelon design for Claybury by some 15 years.
In 2006, the Coulsdon bypass opened, which cut through the foot of the site and also incorporated a roundabout in anticipation of the need to facilitate easier entrance to the site from the main road.
By the time Barratt Homes had purchased the site from English Partnerships and were proposing a comprehensive development, it was clear that housing was the preferred use for the site.
In 2008 the SASS Unit closed, with services absorbed into River House at Bethlem Royal Hospital.
Squibb and Davies Ltd then commenced with demolition.
In 2010, an application was made to erect new farm buildings on the former Portnalls House site in order to relocate the farm tenant whose agricultural tenancy dated back to 1967 when patients ceased providing labour to the hospital farm. This proposal was rejected on account of the impact on the green belt, with the farm eventually moving into a re-developed SASS unit instead, with Glencairn provided as residential accommodation.
In November 2010, the administration building suffered a fire, for which the suspected arson was never proven. The fire was reportedly started in the basement, which is unlikely because it was known to be damp as a result of water ingress from the cavity created when explosives were detonated in that side of the building. The other side of the building was unharmed.
In 2014, Barratt Homes’ and architects HTA’s proposals for the site were approved by the Greater London Authority, who stated “Redevelopment of this derelict site is supported. Although the increase in development footprint is a concern overall very special circumstances have been demonstrated.” The report highlighted that the new buildings would have a footprint of 47,140 sqm against the hospital’s former footprint of 44,486, therefore having no greater impact on the green belt, although it neglected to point out that the buildings would be spread across the farmland and down the drive, rather than solely on the footprint of the former hospital buildings.
In 2020, developer Haxted Homes commenced work on the admin block to convert it to 14 apartments. The buildings’ facade and western wing was retained, with a block being built on the footprint of the eastern wing, which was demolished after the 2010 arson attack.