47. An appeal shall lie to the ¹[the High Court Division] from- (a) the decision of any Court established under this Act, on the ground of the decision being contrary to some law or usage having the force of law, or of a substantial error or defect in the procedure or investigation of the case which may have produced error or defect in the decision of the case upon the merits, and on no other ground; and (b) the granting of leave by any such Court under sub-section (3) of section 29: Provided that such appeal shall be instituted within three calendar months after the decision appealed from shall have been pronounced.