Tom Hanks and Emma Thompson will be in the capital for the last day of the BFI London Film Festival.
The pair will be on the red carpet for the screening of their film Saving Mr Banks, the story of how the movie Mary Poppins was made.
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Pictures of today's events unfolding following a major security incident at the Houses of Parliament.
At least two people have died after a knifeman brought terror to the heart of Westminster.
The Cobra committee brings together government ministers with senior officials of the emergency services and security agencies.