Ah, it's 'threatening, abusive or insulting'
'A person commits an offence if—
(a)the person—
(i)behaves in a manner that a reasonable person would consider to be threatening, abusive or insulting, or
(ii)communicates to another person material that a reasonable person would consider to be threatening, abusive or insulting'
(related to the protected characteristics:
(a)age,
(b)disability,
(c)religion or, in the case of a social or cultural group, perceived religious affiliation,
(d)sexual orientation,
(e)transgender identity,
(f)variations in sex characteristics.'
There are protections for freedom of speech, but these are in the legislation and would come up in court. They're not in the police guidance.