This appeal by certificate granted under Article 133(1)(a) and (c) of the Constitution which is directed against the judgment and decree dated March 25, 1968 of the High Court of Calcutta in Appeal No. 255 of 1963 raises important questions relating to the interpretation of certain provisions of the Bihar Land Reforms Act, 1950 (Act XXX of 1950) (hereinafter referred to as 'the B.L.R. Act ') as also of the Mining Leases (Modification of Terms) Rules, 1956 providing for the modification and alteration of terms and conditions of the mining leases granted prior to the commencement of the Mines and Minerals (Regulation and Development) Act, 1948 (Act 53 of 1948) (hereinafter re ferred to as 'the 1948 Act ') and of the (Act 67 of 1957) (hereinafter referred to as 'the 1957 Act ') which replaced the 1948 Act on June 1, 1958.