Telling the time by the sun’s position in the sky – especially in cloud-prone Britain – seems unlikely ever to have been reliable. But the number of sundials scratched into the walls of churches shows it was once the best or perhaps the only method available.
It was important to the medieval church because mass has to be said at sunrise, mid-morning, noon, mid-afternoon and sunset. So the scratch dial or mass dials still seen on the south side of churches have lines, not for the hours, but so the faithful could tell when these prayers should be said. They are mostly dated between 1100 and 1600, when Henry VIII’s reformation made them redundant.
