And the carvings have inspired a new exhibition which is being staged at the church.
Witch marks were commonplace from the medieval period until the early 19th century and like those at Holy Trinity, were often made next to windows, doorways and fireplaces, perceived as convenient entrance points for demons, witches and evil spirits.
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They continued to be used as symbols of good luck and protection long after the fear of witchcraft and demons had died out.
Now a collection of ceramics, created by volunteer artist-in-residence Iona Stock and inspired by the marks, is on show in the building until Saturday, May 21.
The dozen hand-thrown ceramic vessels which make up the exhibition reflect the shapes of the marks and the natural erosion within plaster, wood and stone in the church.
Iona Stock believes the witch marks and signs of erosion are as much a part of the church as designs produced by the dozens of craftsmen who worked on the building over the centuries.
“This has been absolutely incredible to work on,” she said.
“The original Georgian décor would have been extremely bright and vibrant and there are elements of that peeking through."
Lily Daniels, Participation and Engagement Officer at Seventeen Nineteen, added: “Holy Trinity is a phenomenal space, full of stories and secrets.
“And the work Iona has produced is just the same; filled with detail, character and fascinating ideas. We’re thrilled to support her work and bring her art to the East End.”
Audio tours - are available on site and digitally, along with a booklet exploring themes in the work and exploring ways in which emerging artists can engage with and respond to heritage sites.
The exhibition marks the beginning of a three-year programme of University of Sunderland and Sunderland College student-led activities at Seventeen Nineteen.
For more information visit https://www.visitchurches.org.uk/1719/