Redwood House dates from the 1860s. It was the original building on this site when the Dorset County Asylum moved from its original site at Forston (a couple of miles away). The architect was H E Kendall Junior. It comprised a square block around a courtyard at the centre of which was an octagonal kitchen. There were separate male and female wards connected to the central chapel and workshops in the north corners. It is an important example of mid-Victorian asylum architecture, quite ornate in its brickwork and the tracery of the chapel windows. In later years, other buildings were added elsewhere on the site and the institution was re-named Herrison Hospital. It provided mental health services for the county of Dorset.
The hospital closed in the 1990s and the village of Charlton Down was built over a period of around 10 years, comprising the conversion of the three main hospital ward blocks and the building of new dwellings (houses and flats) elsewhere on the site.
Conversion of Redwood House to apartments began in the late 1990s and the last apartment was occupied in 2003.The conversion was undertaken by a developer called Charlton Down Developments Ltd, (CDDL) who owned the freehold. The first wave of development created 58 apartments. A second wave of 5 brought the total to 63. The final conversion (to create number 64 Redwood House) was undertaken at a later stage.
Redwood House now comprises sixty-four leasehold residences with 999 year leases. One (No.64) is in a stand-alone building at the west end of Redwood House, the rest are located in the various ‘wings’ of Redwood House. These wings are served by 14 separate communal entrances, hallways and staircases, while others (Nos. 1, 41, 59, 60, 63 and 64) each have their own private entrances.