The Mayor's office says that the Northern Line extension will reduce pressure on Vauxhall station and existing Northern Line services, in addition to boosting the area's economy.
It is expected that work on the line could begin by 2015, with services in operation by 2020.
A consultation on the plans is already underway.
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Teenage twin brothers were found guilty today of murdering a 'quiet, humble' father who dared to intervene in a robbery in north London.
The women were reportedly both students at City and Islington College campus in Holloway Road.