An authorised activity for a column 1 resource authority may be carried out in an overlapping area the subject of the resource authority only if—
(a) it does not adversely affect carrying out in the overlapping area an activity that is an authorised activity for a corresponding column 2 resource authority for the column 1 resource authority; and
(b) carrying out the authorised activity for the corresponding column 2 resource authority has already started in the overlapping area.