In 1914 the house was unoccupied and Lord Sherborne, after having been approached by Mary King, not only lent it for use as a Red Cross Hospital but also agreed to have the whole inside painted. It was fitted with electric light and the baths and sanitary accommodation was improved. Standish House Hospital opened as a British Red Cross hospital under the management of Mary King on 13 May 1915. There were 100 beds within the house and 8 fully trained nursing sisters. The rest of the staff was all local volunteers. Patients were wounded soldiers from all over the country. A total of 2,292 sick and wounded soldiers were treated at the hospital during the First World War.
After the war living conditions were very poor which led to a rise in diseases such as tuberculosis. The Government and Local Authorities had a duty to try to improve people's health and so it was proposed that Standish should be opened as a Tuberculosis Institution. Gloucestershire County Council bought Standish Park in its entirety from Lord Sherborne.
The house was turned into a sanatorium to treat tuberculosis in 1922.