(1) Personal data are exempt from any of the provisions of -
(a) the data protection principles,
if the exemption from that provision is required for the purpose of safeguarding national security.
(2) Subject to subsection (4), a certificate signed by a Minister of the Crown certifying that exemption from all or any of the provisions mentioned in subsection (1) is or at any time was required for the purpose there mentioned in respect of any personal data shall be conclusive evidence of that fact.
(3) A certificate under subsection (2) may identify the personal data to which it applies by means of a general description and may be expressed to have prospective effect.
(4) Any person directly affected by the issuing of a certificate under subsection (2) may appeal to the Tribunal against the certificate.
(5) If on an appeal under subsection (4), the Tribunal finds that, applying the principles applied by the court on an applicatio