Today is the start of Road Safety Week and it has seen the launch of an initiative to make 20 miles an hour the limit in the capital's built-up areas.
This report from Glen Goodman.
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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.