A person does not commit an offence under Part 3, 4, 10 or 11 of this Act if—
the conduct which would otherwise constitute the offence takes place on board a vessel (within the meaning of section 353(1)), and
the vessel is on a journey which has taken it or is intended to take it into international waters.
Subject to subsection (1) a provision of this Act which applies in relation to a thing done in Great Britain applies to that thing if done on or in the territorial sea adjacent to Great Britain.
In this section—