Edinburgh Parish Church (later known as St Giles' Church, or Cathedral nowadays) was until some time in the late 19th century divided internally into three churches - High Church, Old Church and New North Church. New North Parish was the area immediately south of the church - a rectangular area bounded by High Street on the north, Blair Street on the east, Cowgate on the south and George IV Bridge on the west.
At the time of the 1841 and 1851 censuses, the "old town" part of Edinburgh Parish was divided into 10 Quoad Sacra parishes - Toolbooth, High Church, Trinity College, St John's New North, Tron, Old Church, New Greyfriars, Old Greyfriars and Lady Yesters. Most of these show up within St Giles registration district in the post-1855 censuses.
ADP