All indictable Offences mentioned in this Act which shall be committed within the Jurisdiction of the Admiralty of England or Ireland shall be deemed to be Offences of the same Nature and liable to the same Punishments as if they had been committed upon the Land in England or Ireland, and may be dealt with, inquired of, tried, and determined in any County or Place in England or Ireland in which the Offender shall be apprehended or be in Custody, in the same Manner in all respects as if they had been actually committed in that County or Place; and in any Indictment for any such Offence, or for being an Accessory to such an Offence, the Venue in the Margin shall be the same as if the Offence had been committed in such County or Place, and the Offence shall be averred to have been committed " on the High Seas :" Provided that nothing herein contained shall alter or affect any of the Laws relating to the Government of Her Majesty's Land or Naval Forces.