law: Indian Post Office Act, 1898 
  10. Power to declare rates of foreign postage 
  (1) Where arrangements
  
  are in force with the United Kingdom, or with any British possession or foreign
  
  country, for the transmission by post of postal articles between 5[India]
  
  and the United Kingdom or such possession or country, the Central Government
  
  may, in conformity with the provisions of such arrangements, declare what
  
  postage rates and other sums shall be charged in respect of such postal
  
  articles, and may make rules as to the scale of weight, terms and conditions
  
  subject to which the rates so declared shall be charged.
  (2) Unless and until
  
  such declaration as aforesaid is made, the existing rates and regulations shall
  
  continue in force.