Boris Johnson has announced a £1.5 billion project to develop the 50 acre site in Silvertown Quays in a scheme that could create up to 9,000 jobs.
The area has been undeveloped for decades but the developers behind the scheme The Silvertown Partnership say London has seen the regeneration of a number of sites across East London such as nearby Canary Wharf and Straford.
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The 24-year-old was unarmed and the incident is not being treated as terror-related.
Some platforms have been taken out of service with disruption expected to continue until the end of the day.
The Met Office has extended its weather warnings for snow and ice to cover vast swathes of the country, including London and the South East.