The Front Cover which would have had the identification of owner is missing.
I thank Hemal Gurusinghe of Australia for the scan with part of the blue upper coupon sheet which in his book has KG on every coupon. The 1949-51 Ration book Coupons posted have CMC for Colombo Municipal Council. KG stands for KurunaGalla matching the last part of word seen on the rubber stamp on the side.