(2) Notwithstanding anything in clause (1), for a period of fifteen years from the commencement of this Constitution, the English language shall continue to be used for all the official purposes of the Union for which it was being used immediately before such commencement: Provided that the President may, during the said period, by order authorise the use of the Hindi language in addition to the English language and of the Devanagari form of numerals in addition to the international form of Indian numerals for any of the official purposes of the Union.