19. (1) All tea purchased in the auction other than those for internal consumption shall be exported by or on behalf of the purchasers within a period of four months from the date of the purchase and every such purchaser shall have the right to obtain an export licence required under section 20 for the quantity to be exported. (2) The Board may, in special circumstances, permit a purchaser to export in lieu of tea purchased in auctions an equivalent quantity of tea purchased otherwise than in such auctions.