This small medieval church was founded by the medieval order of the Knights Hospitallers of St John from where derives the name Johnstown. This order had its headquarters at Kilteel in Kildare and also had an abbey in Naas. In 1212 Pope Innocent III confirmed these lands and the lands at nearby Palmerstown were in the ownership of the Knights, the name Palmerstown originating from pilgrims who returned from the Holy Land with a palm branch or leaf.

By the end of the 13th century a family named Flatsbury/Flatesbury owned much of the area of both Palmerstown and Johnstown however the Knights held on to the church at Johnstown. The Flatsburys were influential throughout the 14th to the 16th centuries, members of the family holding the titles of Sheriffs of Kildare and the Collectors of the Kings Revenue. One of the most striking historical fragments that sit in the church is a stone slab with the coat of arms of the Flatsbury and Wogan families and is said to be the grave slave of James Flatsbury who married Eleanor Wogan in 1436.

The church fell into disrepair following the Dissolution of the Monasteries in the 16th century. After the Rebellion of 1641 the lands of Johnstown and Palmerstown were seized from the Flatsburys and granted to a west of Ireland family named Bourke. The Bourkes became one of the most powerful families in Kildare holding the titles of Lord Naas and the Earl of Mayo. The most famous of the family was the 6th Early, Richard Southwell Bourke who was Chief Secretary of Ireland three times during the 1860s. Bourke later went on to become the Viceroy of India and was assassinated in 1872, he is buried under the Celtic style cross at the centre of the church. The medieval piscina/stone basin is another nice feature of the church as is the tree that seems to have grown around one of the iron posts that surround a grave!

GPS: 53.23697, -6.62119