payable by virtue of that subsection shall be divided between the registered proprietor and the assignor in such proportion as may be agreed upon between them or as may in default of agreement be determined by the High Court on a reference under section twenty-one; and (b) in relation to any use of the design made for the services of the State by the registered proprietor to the order of a Government department, subsection (3) of section eighteen shall have effect as if that use were made by virtue of an authority given under that section. (5) Where, under subsection (3) of section eighteen, payments are required to be made by a Government department to a registered proprietor in respect of any use of a design, any person being the holder of an exclusive licence under the registered design (not being such a licence as is mentioned in subsection (3) of this section) authorising him to make that use of the design shall be entitled to recover from the registered proprietor such part, if any, of those payments as may be agreed upon between that person and the registered proprietor, or as may in default of agreement be determined by the High Court under section twenty-one to be just having regard to any expenditure incurred by that person(a) in developing the said design; or (b) in making payments to the registered proprietor, other than royalties or other payments determined by reference to the use of the design, in consideration of the licence; and if, at any time before the amount of any such payment has been agreed upon between the Government department and the registered proprietor, that person gives notice in writing of his interest to the department, any agreement as to the amount of that payment shall be of no effect unless it is made with his consent. (As amended by S.I. No. 175 of 1965 and Act No. 16 of 1980) 20. (1) In this section, "period of emergency" means any period beginning on such date as may be declared by the Minister by statutory notice to be the commencement, and ending on such date as may be so declared to be the termination, of a period of emergency. Special provisions as to State use during emergency