Kingsley Green is a mental health and learning disability site located in Hertfordshire, England, just southeast of the village of London Colney.

Located on Harper Lane, Shenley, the facility was known as Harperbury Hospital for 61 years and has been a fixture of the area's mental health scene since 1928.

The Royal Flying Corps, who were based at the London Colney aerodrome, used the site as an aircraft storage facility during the First World War.

In 1924 Middlesex County Council purchased Porters Park Estate, totaling 420 acres (170 ha) to create both the Harperbury and Shenley hospitals.

[5][3] Once the new buildings were completed, the institution was renamed Middlesex Colony in May 1936, when the facility was officially opened by Minister of Health Sir Kingsley Wood.

Men also worked in workshops to provide needed goods for the hospital, such as clothes, shoes, brushes and upholstery.

[1] When Minister of Health Enoch Powell visited in 1961, he questioned the future role of large mental hospitals.

[1] In 1965 the Kennedy-Galton Centre opened to study clinical genetics and to diagnose chromosomal abnormalities in the unborn.

[1] By the early 1970s patients were taking part in day trips to visit the shopping areas at nearby St Albans.

Musical events were held at Harperbury and severely handicapped deaf patients were taught the Makaton sign language.

[7] Following the introduction of Care in the Community in the early 1980s, plans were introduced to close the Shenley, Napsbury and Harperbury hospitals.

[8] Thieves ripped out copper wiring that on two occasions resulted in power disruptions and outages at Harperbury.

[9] In May 2009 a new mental health facility was created by converting space in old buildings into what became known as the Oak and Beech Units.

One is a mental health facility that was created by converting space in old buildings into what is known as the Oak & Beech Units.

Another programme is the Specialist Residential Service, which provides medium to long term care for 29 adults with learning disabilities and complex needs.

The programme "aims to provide a service which enables young people and their families to understand and cope with psychological, emotional and behavioural problems which they may be experiencing."

[10] Kingsley Green houses the above mentioned Adolescent Outreach Team, which conducts its work in the outside community.