In addition to being an administrative county with a county council, the 1888 Act also provided that "such portion of the administrative county of London as forms part of the counties of Middlesex, Surrey, and Kent, shall [...] be severed from those counties, and form a separate county for all non-administrative purposes by the name of the county of London".
The county was created as part of the general introduction of county councils and was governed by the London County Council. It did not cover all of today's Greater London, but only the inner part. It covered parts of Middlesex, Surrey and Kent - corresponding to today's London Boroughs of Camden, Greenwich, Hackney, Hammersmith and Fulham, Islington, Kensington and Chelsea, Lambeth, Lewisham, Southwark, Tower Hamlets, Wandsworth and Westminster.
The county did not include the City of London. A Royal Commission on the Amalgamation of the City and County of London was set up to explore the means of amalgamation of the two entities, but was unsuccessful in effecting the change.
In 1900, eleven years after its foundation, the London Government Act divided the County of London into 28 metropolitan boroughs. These replaced the ancient parish vestries and district boards as the second tier of local government. When the County of London was abolished in 1965 these metropolitan boroughs were merged to form 12 London boroughs.
County of London boroughs numbered in the information box on the right side:
| Year | Central Area† | Inner Ring‡ | Second Ring§ | County of London Total | Outer Ring# of Greater London |
|---|---|---|---|---|---|
| 1881 | 1,743,000 | 1,008,000 | 1,093,000 | 3,844,000 | 950,000 |
| 1901 | 1,623,000 | 1,201,000 | 1,601,000 | 4,425,000 | 1,422,000 |
| 1921 | 1,364,000 | 1,186,000 | 1,933,000 | 4,483,000 | 2,993,000 |
| 1931 | 1,260,000 | 1,163,000 | 1,976,000 | 4,399,000 | 3,807,000 |
| 1951 | 738,000 | 927,000 | 1,683,000 | 3,348,000 | 4,998,000 |
†The City of London and the Metropolitan Boroughs of Bermondsey, Bethnal Green, Finsbury, Holborn, St Marylebone, St Pancras, Shoreditch, Southwark, Stepney and Westminster.
‡The Metropolitan Boroughs of Battersea, Chelsea, Islington, Kensington, Lambeth and Paddington.
§The Metropolitan Boroughs of Camberwell, Deptford, Fulham, Greenwich, Hackney, Hammersmith, Hampstead, Lewisham, Poplar, Stoke Newington, Wandsworth and Woolwich.
#Defined as the area of the Metropolitan Police district outside the County of London.
The county was abolished in 1965 and was replaced by the much larger Greater London, which took in nearly all of Middlesex, along with areas previously in Surrey, Kent, Essex and Hertfordshire.
Since the Greater London Council was not an education authority, but London County Council had been, an Inner London Education Authority was constituted to continue this role for the area of the old County of London, and this continued until 1990.