6(1)A person may be detained—
(a)in right of an arrest under section 7 of this Act, or
(b)under any provision contained in or made under section 8 of this Act, or Part I of this Schedule,
in such place as the Secretary of State may from time to time direct (when not detained in accordance with an order under section 8 of this Act on board a ship or aircraft).
(2)A person shall be deemed to be in legal custody at any time when he is so detained.
(3)Where a person is so detained, any examining officer, constable or prison officer, or any other person authorised by the Secretary of State, may take all such steps as may be reasonably necessary for photographing, measuring or otherwise identifying him.