The officers are protesting against proposed changes to their pay and conditions.
Some 20,000 officers from all 43 forces across England and Wales are thought to be taking part in the first police march in the capital for more than four years.
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Police have released 12 images of people wanted in connection with what they describe as 'disorder' at a McDonalds in central London.
A man in his late 20s was taken to hospital last night after he was stabbed in east London.
Jeremy Corbyn will call for a new wave of grassroots support as he launches his leadership campaign today.