The diocese covers 458 km2 (177 sq mi) of 17 boroughs of Greater London north of the River Thames (historically the City of London and the County of Middlesex) and a small part of the County of Surrey (the district of Spelthorne, historically part of Middlesex).

[11] The present structure of St Peter upon Cornhill was designed by Christopher Wren following the Great Fire in 1666 and stands upon the highest point in the area of old Londinium, but possibly more significantly directly above the location of a pagan shrine room (aedes) within the great Roman London basilica.

[19] Whether the Lucius story is a fiction, or whether there was actually a church deliberately erected over the shrine room is unclear and could only be settled by archaeological exploration under St Peter's.

However, it is interesting that whilst four medieval churches were built around the same time on the foundations of the Roman Basilica and forum, the London city authorities in 1417 determined that St Peter's dated back to Roman times, and indeed was the original seat of English Christianity.

In 1995, a large and ornate 4th-century church was discovered on Tower Hill, which seems to have mimicked St Ambrose's cathedral in the imperial capital at Milan on a still-larger scale.

Following the establishment of the archdiocese of Canterbury by the Gregorian mission, its leader St Augustine consecrated Mellitus as the first bishop to the Saxon kingdom of Essex in 604.

[24] Although it is not clear whether Lundenwic or Lundenburh was intended, it is generally assumed the church was located in the same place occupied by the present St Paul's Cathedral on Ludgate Hill in London.

[citation needed] The Report of the Commissioners appointed by his Majesty to inquire into the Ecclesiastical Revenues of England and Wales (1835), noted the annual net income for the London see was £13,929.