Great Britain’s administrative geography is rather complicated, particularly for England – some English areas are “three tier”, made up of counties which are subdivided into districts, and others are “two tier” consisting of unitary authorities. Then there’s London’s boroughs which are in a special category of their own as part of an authority.
The Ordnance Survey Open Data release (easy download page here) includes BoundaryLine, which includes the geography data file for the counties, and a separate for the districts, UAs and boroughs. The latter is complete (and also includes the Scottish and Welsh regions), but the former looks rather strange on a map, with “islands” of counties separated by a “sea”.
I received a request by someone who was interested in having a unified file, at county level for the non-GLA counties, but including the UAs and London boroughs to “fill in” the map. I’ve made such a file by doing a dissolve in Quantum GIS (the districts having the county name as an attribute), and it can be downloaded here (15MB zipped shapefile.) The data is derived from and therefore covered by the OS Open Data licence which requires simply that the original source must be attributed when using it – that is, the data contains Ordnance Survey data © Crown copyright and database right 2010.
The image above is showing the merged data, with the unmerged district data (dotted lines) superimposed.