Harry is correct: The Problem does go back to MacPherson, Recommendation 12, Page 376:
DEFINITION OF RACIST INCIDENT
12. That the definition should be:
"A racist incident is any incident which is perceived to be racist by the
victim or any other person".
assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/277111/4262.pdf
It is ambiguous, but for the incident to be perceived as racist there must be an "incident." (13) says an incident need not be a crime, but does not say what it needs to be.
It would have helped if the definition had said "any (other) reasonable person, where perceptions in law are founded on the persepective of a resonable person, a circular definition, a reasonable person is a person who is reasonable, but one which a jury can consider.