London borough boundaries

London Borough Boundaries are the key admin boundaries within the greater Greater London statistic region, subdividing it into 33 "boroughs" or "cities" (administratively assimilated to unitary autorities in other English counties, but not subdivided into districts; for this reason, these boroughs are indifferently tagged in OSM as districts).

Classification and tagging in OSM

In these 33 subdivisions of the region:

• Two of them (London, and Westminster) are qualified as "cities", and could be tagged with council_style=city; the 31 other subdivisions are qualified as "boroughs" (including the 2 "royal boroughs" of Greenwhich, and Kensington and Chelsea), and could be tagged with council_style=borough.
• Only the City of London is also a ceremonial county (tagged in OSM at admin_level=6); the other 32 "boroughs" (tagged in OSM at admin_level=8) are grouped together in the separate ceremonial county of Greater London (also tagged in OSM at admin_level=6).
• The node currently used in OSM for the place named "London" (tagged with place=city), and used for the national capital and region capital ( admin_centre in relations), actually does not fall within the City of London, but in the City of Westminster.

Although these subdivisions are often named borough, their official status is a London borough (with the exception of the City of London which remains separated), because most of them are grouping several former boroughs (including today's City of Westminster); they all qualify as local authority districts'.

Before their merging into London boroughs, they were historically categorized by a inner (part of the former Inner London area) or outer (part of the former Outer London area) and had various status (metropolitan borough within Inner London, or municipal boroughs, county boroughs, and urban districts within Outer London) designation. The designation is still present in today's London boroughs (11 are inner including the City of London, 22 are outer), but gives no other functional distinction on the operation of their local council.

Boundaries between the London boroughs have been tagged boundary=administrative and left:district=name right:district=name but this is deprecated as we can determine them now using boundary relations in OSM.

List of London boroughs

A relation of London Borough Boundary relations London Borough Boundary relations is available for reference (it should include all the 33 boroughs, including the City of London which also inherits the designation of Inner London borough; but it is still incomplete, and also includes a member for the Greater London ceremonial county separated from the City of London).

Notes

Note that most online maps showing the position of the borders are copyrighted. Even supposedly open licensed maps on wikipedia are actually derived from copyrighted sources. As of February 2013, all the boundaries are mapped from the most accurate source which we can use at the moment - OS Boundary Line data. Ideally we'll keep it clean by surveying signs in the streets. Keep a look out for those "Welcome to London Borough of X" signs while you're out and about.

According to the OS Boundary Line data, the boundary between Southwark and the City of London is roughly the centre-line of the Thames. However the City of London Corporation controls (through Bridge House Estates) the whole of London Bridge so the boundary has been adjusted in OSM to cover the whole bridge. A similar situation exists at Blackfriars Bridge, although this is reflected in the OS data.

External links

• The OSM Inspector tool is excellent for checking that a boundary is complete and that all the tagging of the ways and relation is correct.
• Wikipedia has a rather comprehensive list of  boundary changes within London, which links to the relevant governmental orders which made the change. Although many refer to maps not included, the explanatory notes may assist mapping of both the Greater London and borough boundaries.

References