4.—(1) All frontier control enactments shall for the purpose of enabling officers belonging to the United Kingdom to carry out frontier controls extend—
(a)to France within a control zone, and
(b)to Belgium within a control zone.
(2) Data used or processed in a control zone in Belgium, in connection with his responsibilities or duties, by a person who by virtue of section 38 of the Data Protection Act 1984(1) (“the 1984 Act”) falls to be treated for the purposes of the 1984 Act as a servant of a government department, or of a chief officer or other person or authority mentioned in subsection (3) of that section, shall be treated—
(a)for the purposes of section 39(1) of the 1984 Act, as being held in the United Kingdom, and
(b)for the purposes of section 39(5), as being used or intended to be used in the United Kingdom,
and the 1984 Act shall accordingly apply to the data.
(3) Data used or processed in a control zone in the United Kingdom, in connection with his responsibilities or duties, by an officer belonging to the Kingdom of Belgium shall be treated—
(a)for the purposes of section 39(1) of the 1984 Act, as being held outside the United Kingdom, and
(b)for the purposes of section 39(5), as not being used or intended to be used in the United Kingdom,
and the 1984 Act shall accordingly not apply to the data.