The church is mainly granite, including the piers, so it is perhaps not surprising that the only graffiti found is on the timber screens. This includes two identical motifs which could be read as I X Christograms (the Greek letters for Jesus Christ), although we can’t be sure that the maker would have known this symbolism. The motifs are, however, carefully executed and clearly had some significance and purpose. It is interesting that they both have the central vertical stroke offset to the right.
The remaining graffiti consists of marks commonly associated with a protective function – namely, irregular grids and scored lines, and the single letters W and V and a ladder (or tally marks).
Devon Historic Graffiti Survey https://devonhistoricgraffiti.org.uk/manaton-st-winifred