In 1896, the Metropolitan Asylums Board [MAB] acquired a 136-acre site at Carshalton on which they intended to construct a 800-bed convalescent hospital, to be known as the Southern Hospital.
Buildings for this purpose were erected on the site in 1907-8. However, on 1st September 1908, the MAB was given the additional responsibility of dealing with "sick or convalescent or debilitated children".
It was therefore decided to adapt Carshalton as a general hospital for one thousand children under the name of the Children's Hospital.
The former Gore Farm Hospital at Darenth, previously mainly used by convalescing smallpox patients, took on a more general convalescent role and also inherited the name of the Southern Hospital. In 1914, following the accession of King George the Fifth and Queen Mary to the throne, the Children's Hospital was renamed Queen Mary's Hospital for Children.
At the entrance to the site at the north were placed the hospital's administrative block, together the kitchens, laundry, staff blocks, medical superintendent's house, and porter's lodge. The children were accommodated in 24 pairs of U-shaped single-storey cottages, arranged in three echelons. Each group of four cottages was accompanied by a staff house.
Two hospital blocks for surgical cases were placed at the south of the site. Queen Mary's was also home to the first MAB training school for nurses.In 1959, the Fountain Hospital for mentally handicapped children was to transferred to the Queen Mary site to create the first fully comprehensive children's hospital in the United Kingdom.
The eastern part of the hospital site has now been redeveloped for residential use and the hospital buildings demolished. The administrative block, superintendent's house, community hall, and a number of other blocks still survive.