There are already a number of offences which may be relevant, including:
- encouragement of terrorism, contrary to section 1 Terrorism Act 2006;
- disseminating terrorist publications, contrary to section 2 Terrorism Act 2006;
- inviting support for a proscribed group, contrary to section 12 Terrorism Act 2000; and
- displaying an item in circumstances arousing a reasonable suspicion that a person belongs to or supports a proscribed group, contrary to section 13 Terrorism Act 2000.
It would be for the police and CPS to investigate and charge any offences, as appropriate.