City and South London Railway

The City and South London Railway (C&SLR) was the first successful deep-level underground "tube" railway in the world, and the first major railway to use electric traction. The railway was originally intended for cable-hauled trains, but owing to the bankruptcy of the cable contractor during construction, a system of electric traction using electric locomotives – an experimental technology at the time – was chosen instead.

When opened in 1890, the line had six stations and ran for 3.2 miles (5.1 km) in a pair of tunnels between the City of London and Stockwell, passing under the River Thames. The diameter of the tunnels restricted the size of the trains, and the small carriages with their high-backed seating were nicknamed padded cells. The railway was extended several times north and south, eventually serving 22 stations over a distance of 13.5 miles (21.7 km) from Camden Town in north London to Morden in south London.

Although the C&SLR was well used, low ticket prices and the construction cost of the extensions placed a strain on the company's finances. In 1913 the C&SLR became part of the Underground Group of railways, and in the 1920s it underwent major reconstruction works before its merger with another of the Group's railways, the Charing Cross, Euston and Hampstead Railway, forming a single London Underground line called the Morden–Edgware line. In 1933, the London Passenger Transport Board was created by amalgamation of the C&SLR with the rest of the Underground Group, bus and other transport companies. This was a public authority but not nationalised until 1948 with the creation of the British Transport Commission. Today, its tunnels and stations form the Bank Branch of the Northern line from Camden Town to Kennington and the southern leg of the line from Kennington to Morden.