11(1)Paragraph 6 material may be retained for as long as a national security determination made by the responsible chief officer of police has effect in relation to it.
(2)A national security determination is made if the responsible chief officer of police determines that it is necessary for any paragraph 6 material to be retained for the purposes of national security.
(3)A national security determination—
(a)must be in writing,
(b)has effect for a maximum of 2 years beginning with the date on which the determination is made, and
(c)may be renewed.