13. - (1) A person in a public place commits an offence
if he-
(a) wears an item of clothing, or
(b) wears, carries or displays an
article,
in such a way or in such circumstances as
to arouse
reasonable suspicion that he is a member
or supporter of a
proscribed organisation.
(2) A constable in Scotland may arrest
a person without
a warrant if he has reasonable grounds to
suspect that the
person is guilty of an offence under this
section.
http://www.legislation.hmso.gov.uk/acts/acts2000/00011--c.htm#11
Other tidbits:
58. - (1) A person commits an offence if-
(a) he collects or makes a record of
information of a kind
likely to be useful to a person
committing or preparing an
act of terrorism, or
(b) he possesses a document or record
containing
information of that kind.
(2) In this section "record" includes a
photographic or
electronic record.
(3) It is a defence for a person charged
with an offence
under this section to prove that he had a
reasonable excuse for
his action or possession.
89. - (1) An officer may stop a person for so long as
is necessary to question him to
ascertain-
(a) his identity and movements;
(b) what he knows about a recent
explosion or
another recent incident endangering
life;
(c) what he knows about a person
killed or
injured in a recent explosion or
incident.
(2) A person commits an offence if
he-
(a) fails to stop when required to
do so under this
section,
(b) refuses to answer a question
addressed to him
under this section, or
(c) fails to answer to the best of
his knowledge
and ability a question addressed to
him under this
section.
