As a hospital

In the mid 12th century, during the reign of Henry II, the land on which St. John's House stands was given to the establishment of the Hospital of St. John the Baptist. The hospital was brought into being by William de Beaumont, then Earl of Warwick. This hospital provided two purposes: To help the local poor and ill; and to provide casual overnight boarding and food to impoverished travellers such as pilgrims.^[2] The Hospital of St. John the Baptist was one of two such hospitals in the town of Warwick at the time. The other was St Michael's Leper Hospital, founded with the sole purpose of providing help and respite to those in the parish suffering from leprosy. Of both hospitals, only the chapel building of St. Michael still stands.^[3]

In 1291's taxatio, the Hospital was noted to own a dovecote worth 2 shillings. Additionally, the carucate of land owned by the Hospital was valued at 10 shilling per year. In 1337, protection was granted to the hospital's brethren and their attorneys for the collection of alms at churches. At this time it was suggested that some building renovation was necessary.

It is known that in 1610 the site comprised four standing buildings, including a gatehouse topped with crenulations. The largest of the three other buildings has crosses at the roof's apex, suggesting its religious use as the site's chapel.^[4] At the time the hospital site also included a cemetery - remains have often been dug up during refurbishment or remodeling works on the House. The first recorded case was in the 1830s when work was being undertaken in the kitchen garden. In 1987, two workmen digging to the Coten End front of St. John's Court flats discovered two skulls.^[5]

As a residence

During the Dissolution of the Monasteries at the behest of Henry VIII, St. John's was granted to Anthony Stoughton, for services to the King. The land was later passed to his eldest son William by inheritance. Neither of the two lived in the house, but they leased it out to others such as Richard Townsende, a yeoman at Warwick. Eventually the land was inherited by the son of William Stoughton, Anthony Stoughton (junior), who built a house on the site. Of note is the fact that in the East Wing of the house there is a door lintel which bears the date 1626 and the initials A.S.. The house remained in the possession of the Stoughton family until 1960.^[6]

As a school

In 1791, the building was rented out for the first time by the Earl of Warwick for public use, with the intent of converting it into a school. The school, then known as St John's Academy, was founded by William T Fowler and was set up as a school for "Young Gentlemen" (as advertised on the hand-bill^[7] This was then reverted in 1845 under Benjamin Townsend, the son-in-law of William Fowler.^[8] After Townsend's death in 1857, three of his daughters, Susanna, Elizabeth and Sarah, took over the running of the school, with it being a girls' school from at least 1861.^[9]

As a public service

After a brief spell of private tenancy in the start of the 20th century, the house became the property of the War Department, where it was used for the administration of the Home Counties and East Anglian Brigades. In 1959 the Lord Warwick declared the sale of the Warwick Castle Estates, including the St. John's House. The building was then turned into a museum, with some of the premises leased to the Regiment Royal Warwickshire Regiment. The museum was officially opened in 1960 by Bernard Montgomery, 1st Viscount Montgomery of Alamein. In 2016 the Museum ceased to be open to the general public.^[10]