(1)A power conferred by virtue of this Act on a constable—
(a)is additional to powers which he has at common law or by virtue of any other enactment, and
(b)shall not be taken to affect those powers.
(2)A constable may if necessary use reasonable force for the purpose of exercising a power conferred on him by virtue of this Act (apart from paragraphs 2 and 3 of Schedule 7).
(3)Where anything is seized by a constable under a power conferred by virtue of this Act, it may (unless the contrary intention appears) be retained for so long as is necessary in all the circumstances.