As I understand it, it's generally legal to photograph someone in public, because consent can be assumed. It has to work this way because otherwise it'd be impossible for e.g. journalists to take a photo of a rally.
Question: can the photographer still take the photograph if they are told "I do not consent to being photographed"? If the answer is 'yes they can still take the photograph', does telling the photographer "I do not consent to being photographed" change anything at all?