When the system was first designed, it was
planned that further extensions would be built at a later date. The proposal
was that after a few years of operation of the first section, testing out the various
systems and stock used, that 3 extensions would be built.
These comprised a direct line from King Edward Building to West Central District Office, continuing to the South Western District Office at Howick Place, near
Victoria. A loop line from Mount Pleasant to Euston, the North Western District Office in Eversholt Street, St. Pancras, Kings Cross, and back to Mount Pleasant; one from Mount Pleasant to the Northern District Office in Upper Street; lastly one from King Edward Building to Cannon Street, London Bridge, the South Eastern District Office in Borough High Street, the South Eastern Parcels Office, Waterloo, and the South Western District Office.
Although nothing ever came of these proposed extensions,
they were kept in mind for a surprisingly long time. Short sections of the
extension were started whilst the main section was being built, most notably
at Mount Pleasant, but only extended a few yards.
Even in recent times, proposals were made
to extend the line to the new central sorting hub at Willesden. Needless to
say this was abandoned due to the estimated cost of the extension. At the
time, it cost
over a million pounds per mile to excavate a deep level tube tunnel.
