Where a patient is admitted to a hospital in pursuance of an application (other than an emergency application) made under Part IV of the principal Act by his nearest relative, the managers of the hospital shall as soon as practicable give notice of that fact to the local social services authority for the area in which the patient resided immediately before his admission; and that authority shall as soon as practicable arrange for a social worker of their social services department to interview the patient and provide the managers with a report on his social circumstances.