To clarify the man was already red, and the law is here:
https://www.gov.uk/rules-pedestrians-1-to-35/crossings-18-to-30
The only law on that page is that it's illegal to loiter on a crossing.
@Brun started
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To clarify the man was already red, and the law is here:
https://www.gov.uk/rules-pedestrians-1-to-35/crossings-18-to-30