@Museumcurry Causing stress and upset to someone is not a reasonable threshold for arrest. I hope that's obvious.
Probably charged with Section 5 of the Public Order Act 1986
A section 5 offence comprises two elements:
A person must (a) use threatening, abusive or insulting words or behaviour, or disorderly behaviour, or (b) display any writing, sign or other visible representation which is threatening, abusive or insulting; and
The words or behaviour, or writing, sign of other visible representation must be within the hearing or sight of a person likely to be caused harassment, alarm or distress thereby.
Hope it is obvious now.