If you want to see 15th century graffiti and murals, then you need to visit the Church of St. Vincent in north Hertfordshire.
The church was visited by medieval pilgrims on their way down to worship at the shrine of St. Alban in the ‘Abbey of St. Albans’. The pilgrims often etched small votive crosses into the stonework to leave their mark.
In medieval times, English churches would have been very colourful places, full of murals depicting scenes from the bible and saints. St. George killing the dragon was a popular mural in english churches. The murals in St. Vincent were rediscovered in the 1960’s during renovation work.
Have a look at my video here: