This is the 15th century church of St Mary by the Walls, mentioned in the story. You can clearly see the extensive damage that was caused in 1648 when the Parliamentary forces concentrated their fire at the church because Thompson, the one eyed gunner in charge of the cannon, said to be 'Humpty Dumpty', was causing such damage to Lord Fairfax's attacking forces. Eventually, Thompson and his cannon, came tumbling down. The tower was repaired around 1750 in brick, instead of the re-used Roman materials with which the rest of the tower is constructed.