(1)Proceedings under this Part of this Act or Schedule 3 in respect of an offence on a ship may be taken, and the offence may for all incidental purposes be treated as having been committed, in any place in the United Kingdom.
(2)No such proceedings shall be instituted—
(a)in England or Wales except by or with the consent of the Director of Public Prosecutions or the Commissioners of Customs and Excise;
(b)in Northern Ireland except by or with the consent of the Director of Public Prosecutions for Northern Ireland or those Commissioners.
(3)Without prejudice to subsection (2) above no proceedings for an offence under section 19 above alleged to have been committed outside the landward limits of the territorial sea of the United Kingdom on a ship registered in a Convention state shall be instituted except in pursuance of the exercise with the authority of the Secretary of State of the powers conferred by Schedule 3 to this Act; and section 3 of the [1878 c. 73.] Territorial Waters Jurisdiction Act 1878 (consent of Secretary of State for certain prosecutions) shall not apply to those proceedings.