St Mark's Mission Church was located on the east side of Hill Street (B4256). The building originated as an infants' school before 1878. By about 1900 the building had been extended to become a Mission Room, and by about 1920 this had become the Mission Church. It appears to have been demolished in the post-War period.
Map depictions and an early line drawing show a building of irregular shape, long axis aligned north-west by south-east. It appears to have been a whitewashed building with a slate roof and bellcote towards its west end, and lit through lancet windows.
Sources:
Ordnance Survey County Series 25-inch maps: sheet Monmouthshire XVI.4, editions of c.1878, 1900 & 1920.
NMRW archive, photo 970607-31.

David Leighton, RCAHMW, 27 November 2015