https://www.met.police.uk/advice/advice-and-information/ph/photography-advice#
Freedom to photograph and film
Members of the public and the media do not need a permit to film or photograph in public places and police have no power to stop them filming or photographing incidents or police personnel.
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The press and the public
If someone distressed or bereaved asks the police to stop the media recording them, the request can be passed on to the media, but not enforced.