M25 motorway re-examined as a motorway route in Sir Charles Bressey's and Sir Edwin Lutyens' "The Highway Development Survey, 1937". Sir Patrick Abercrombie's "County of London Plan, 1943" and "Greater London Plan, 1944" proposed a series of five roads encircling the capital. The northern sections of the M25 follow a similar route to the World War II Outer London Defence Ring, a concentric series of tanks and pillboxes designed to slow down a potential German invasion of the capital. Little was done to progress these plans until the 1960s when the Greater London Council developed its London Ringways plan consisting of four
London Underground Transport, and discontinued the use of the London Transport brand in favour of its own brand. The transfer of responsibility was staged, with transfer of control of the London Underground delayed until July 2003, when London Underground Limited became an indirect subsidiary of TfL. Between 2000 and 2003, London Underground was reorganised in a Public-Private Partnership where private infrastructure companies (infracos) upgraded and maintained the railway. This was undertaken before control passed to TfL, who were opposed to the arrangement. One infraco went into administration in 2007 and TfL took over the responsibilities, TfL taking over the other in 2010.