654 The State Government however went back upon this assurance and a letter dated 20th January, 1970 was addressed by the 5th respondent intimating that the Government had taken a policy decision that new Vanaspati Units in the State which go into commercial production by 30th September, 1970 would be given partial concession in Sales Tax at the following rates for a period of three years: First year of production 31/2% Second year of production 3% Third year of production 21/2% The appellant by its letter dated 25th June, 1970 pointed out to the Secretary to the Government that the appellant proposed to start commercial production of Vanaspati with effect from 1st July, 1970, and stated that, as notified in the letter dated 20th January, 1970, the appellant would be availing of the exemption granted by the State Government and would be charging sales tax at the rate of 31/2% instead of 7% on the sales of Vanaspati manufactured by it for a period of one year commencing from 1st July, 1970.