PART IIAuthorities and General Principles of Co-operation
Article 3
(2) Each of the Governments shall designate the authorities or persons having charge of the services which in its territory have responsibility for the exercise of frontier controls and the maintenance of law and order.
Article 4
On non-stop trains, British officers may exercise frontier controls in Belgian and French territory, and Belgian officers in British and French territory.
Article 5
It is agreed that the frontier controls relating to non-stop trains shall in principle be effected under the exclusive responsibility of the British and Belgian authorities.
Article 9
The officers of the three States shall be authorised to circulate freely over the whole of the route between London and Brussels for official purposes simply by producing appropriate evidence of their identity and status.