The earliest, and only medieval, part of the building is the tower which was either constructed or restored in 1465....The original parish was rural, stretching from the city walls of Rochester in the north to Borstal in the south. During the 18th and 19th centuries the City of Rochester expanded south into the parish. Expansion of Rochester to the north and west is blocked by the River Medway and to the east by Chatham. The medieval church became inadequate for the growing population and in 1823 rebuilding started. The new nave was complete the following year, the original chancel, tower and side chapels being retained. With the exception of the tower the medieval buildings were demolished a few years later and by 1840 the basic fabric of the present building was complete. A new east window was installed in 1872.