The exact date on which the Order of the Hospital of St. John of Jerusalem first came into being is unknown, but can be regarded as being about 1080, when a hospice in Jerusalem for Christian pilgrims was established and staffed by monks from a neighbouring Benedictine abbey.  The hospice soon developed into a proper hospital and in 1113 the Pope confirmed its independence.  Over the next forty years it evolved into a religious order, the brothers and sisters of which (commonly known as Hospitallers of St. John) provided care to poor and sick persons of any faith.  They also took on the additional role of defending all Christians when they were threatened. 

Driven from Jerusalem in 1187 the Order established its headquarters on the coast of Palestine, before moving to Cyprus, then to Rhodes, and in 1530 to Malta, over which it assumed full sovereignty.  It governed the Maltese archipelago until it was expelled by Napoleon in 1798.

 From its beginnings the Order grew rapidly and was granted land throughout Western Europe.  Its estates were managed by small groups of brothers (and sisters) who lived in communities known as Commanderies or Preceptories, the purpose of which was the provision of resources to the headquarters of the Order.  These Commanderies came to be gathered into provinces called Priories or Grand Priories.  The estates in Britain were at first administered from a Commandery which was established at Clerkenwell, London, in about 1140.  The original Priory Church was built at that time.  The Order’s landholdings in Britain soon became extensive enough to require management by several Commanderies.  The Commandery at Clerkenwell was elevated into a Priory in 1185, with responsibilities over the Commanderies in Scotland and Wales as well as those in England.  (Ireland became a separate Priory.)  In 1540 the Order was suppressed by King Henry VIII, as part of the process known as the Dissolution of the Monasteries.  It was restored by Queen Mary I in 1557, but Queen Elizabeth I again confiscated all its estates in 1559.    The Scottish properties were laicized in 1565.  The Order in Britain thereafter fell into abeyance

The religious Order of the Hospital of St. John, which is now known as The Sovereign Military Hospitaller Order of St. John of Jerusalem, of Rhodes and of Malta, suffered a period of disarray following its expulsion from Malta, but in the middle of the nineteenth century it was reconsolidated, with headquarters in Rome.  It is still often called “The Order of Malta” and its members are frequently referred to as “Knights of Malta”.

In the 1820s those Knights of Malta who were residents in France offered on their own initiative knighthoods to certain persons in Great Britain, irrespective of their Christian denomination.  Their approach was not part of the official policy of the Order of Malta, but the group of English Knights which was thereby formed. They devoted themselves to charitable activities, including what were to become The St John of Jerusalem Eye Hospital Foundation, which was established in 1882, and The St. John Ambulance Foundations, one concerned with training the public in first aid, which was established in 1877, and the other, concerned with providing first aid care to the public, which had its origins in 1873 and became a Foundation in 1887.  It was this English body, engaged in very substantial charitable activities, which Queen Victoria recognised and incorporated in 1888 and which became the modern Order of St. John. 

Source:  The Order of St. John Guidance Notes for Candidates for Admission to the Order.