
County of London Plan

The County of London Plan was prepared for the London County Council in 1943 by John Henry Forshaw (1895–1973) and Sir Leslie Patrick Abercrombie (1879–1957)
Its main purpose was to point out the main directions of development and reconstruction of London, which in the past decades had faced big changes and irregular growth. It was prepared in anticipation of the end of World War II and the reconstruction after bomb damage and large movements of population.
It focused on five defects, for which it proposed remedies:
Ring roads.
One of the solutions was ring roads around the capital. Construction would have involved considerable disruption, even through parts of the city damaged by bombs, and the roads were not built, but the "C Ring" (the third ring out from the city centre) was to include what is now the South Circular Road. The plan to build a high-quality road was not realised but the semi-circular route was assigned to existing roads through the southern suburbs. A similar plan was revisited in the 1960s under the name of the London Ringways.
Predecessors.
In 1905, the Royal Commission on London Traffic issued a report recommending improvements to road, tram and rail services including a "circular road about 75 miles in length at a radius of 12 miles from St Paul's".
In 1937, the Ministry of Transport published "The Highway Development Survey" by Sir Edwin Lutyens and Sir Charles Bressey, which reviewed London's road needs and recommended the construction of many miles of roads and the improvement of junctions at key congestion points. Among the proposals was a series of orbital roads around the city with the outer ones built as American-style parkways - wide, landscaped roads with limited access and grade-separated junctions.
Rail services.
The report recommended electrification of all rail routes and removal of viaducts, with the elimination of rail bridges over the Thames a key priority. It was hoped that the removal of the river bridges would enable the redevelopment of the South Bank. 
The proposals included a highly ambitious system of two-track bored rail tunnels in loop-shaped routes beneath built-up areas, large enough to handle main-line trains. These tunnels would provide tube-like service but without the need to change from a main-line train to a tube train. As a result, some tube routes would be transformed into freight-only routes, with the northern portion of the Circle line specifically mentioned in this regard.
The proposed railway tunnels would have been as follows:
an “Inner Ring” and an “Outer Ring” of freight-only railways was proposed:
These proposals were further reported on in May 1946 by the Railway (London Plan) Committee, which had been appointed by the Minister of War Transport in February 1944. It was chaired by Sir Charles Inglis. The committee concluded that the cost and time required to carry out the recommendations of the London plan meant that the proposals would not be achievable in a short period of time and could not be carried out until adequate alternative capacity could be provided. Of the four central proposals the one supported by the committee was the North-South Tunnel. The 1946 report recommended a dozen new routes totalling over 100 miles, estimated to cost £230m and take at least 30 years to build. Among them were 'route 8', from East Croydon to Finsbury Park, in tunnel from Norbury via Streatham, Brixton and the Victoria line route, except Victoria-Hyde Park Corner-Bond St-Euston.