In 1962 excavations inside the Church revealed it had three stages of development.
The first stone Church was a church of antae, a type well known in Ireland, in which the side walls project beyond the line of the gables.
The walls were constructed of roughly dressed blocks of red sandstone, which can still be seen to a height of 2 feet along the north and south walls.
The internal measurements of the Church were approximately twenty seven feet and six inches by eighteen feet.
Restoration work carried out in 1873 revealed an altar slab belonging to the 10th or 11th century.
The first Church was rebuilt in the 12th century. It is not known what disaster happened, but it is thought to be connected to the arrival of King Magnus of Norway in 1098 and his construction of fortifications on the isle.
The new walls were raised in herring bone masonry of red sandstone on the stumps of the old walls and the Church was extended to the west, with a new door made in the west gable.
The herring bone masonry can still be seen on the south side. This technique was used in the early Norman period in England, and is probably due to Olaf I (1103 - 1153) who was at the court of Henry I of England, before he became King of Mann.
The third stage appears dated by style to the 15th century. It consists of an eastwards extension of grey slate, with a new east wall having a large window of four or five lights.
A new door was added into the west end of the north wall, which obliterates evidence of the first Church and its westward extension. The stepped platform on the outside of the south wall was used to make announcements from the Church when the Church became the Parish Church of Patrick.
An illustration of the Church in the 17th century shows it to be in good repair and still roofed. However, by 1774 the Church was roofless and in a state of decay, very probably as a consequence of the new parish church being built in 1710.