Between 1883-86, a route was planned by the City and South London Railway (C&SLR), then known as the City of London & Southwark Subway (CL&SS), from King William Street via Elephant & Castle[REF] to Stockwell[REF][REF] and Clapham Common [REF].
In 1912, the C&SLR submitted another bill to increase its capacity by enlarging its tunnels to the larger diameter used for the tunnels of the more recently built railways to allow larger, more modern rolling stock to be used [REF].