Thetford Priory of the Canons of the Holy Sepulchre dates from the 12th century. As you would expect, ghostly monks have been seen walking through he ruins. Chanting has also been heard. A group of teenagers claimed to have seen one monk running through the grounds in 1992. Jangling keys heralded his appearance.
On another occasion, a monk was seen standing in an upstairs window. The full account can be read by clicking here LINK
Apparently, summer evenings are the ideal time to see and hear the phantom brothers.