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 engineering stock London Underground engineering stock Over the years, London Underground has acquired various types of engineering stock to help with the construction of new lines and maintenance of existing lines. Some of these wagons were inherited from its predecessors, many were built new and some were acquired second-hand from the main-line railways. Several types of specialist wagons have been used, which are described below. London Underground uses a numbering system comprising the wagon number prefixed with a letter which designates the wagon's type. These are summarised below. London Underground has used various designs of brake van. They were used for the