There has been a church on the site of St Mary’s for more than 1200 years.  The original 8th Century Saxon church was dedicated to St Gregory but has disappeared over the centuries as the fortunes of the parish expanded. It is known that King Canute was in possession of Staindrop and Staindropshire and that he gave these holdings to the newly founded priory at Durham.  The Bishop soon took possession himself before they were once again returned to the priory.  In 1131 possession of the lands came to Dolphin, son of Uchtred and with the development of the manor and then castle at Raby, the fortunes of the parish and the church were linked to those of Raby and its Castle, which in time meant those of the powerful Neville family.

Following the disastrous Rising of the North, the church and parish suffered some neglect until Sir Henry Vane, an important member of the household of Charles I purchased the the castle and lands from the King in 1626.

With this background the church underwent huge reconstruction throughout the 11th - 15th centuries.  The small Saxon building which had already been enlarged gave way to a much larger construction until following the establishment of a College by Ralph Nevill, Earl of Westmoreland in 1408.