(3) “Fiscal warehouse” means such place in the United Kingdom in the occupation or under the control of the fiscal warehousekeeper, not being retail premises, as he shall notify to the Commissioners in writing; and such a place shall become a fiscal warehouse on receipt by the Commissioners of that notification or on the date stated in it as the date from which it is to have effect, whichever is the later, and, subject to subsection (6) below, shall remain a fiscal warehouse so long as it is in the occupation or under the control of the fiscal warehouse keeper or until he shall notify the Commissioners in writing that it is to cease to be a fiscal warehouse.