Section 72(4) in The West Bengal Non-Agricultural Tenancy Act, 1949
(4)Notwithstanding anything contained in any other law for the time being in force or in any contract, where any land which is not non-agricultural land is converted into a tenancy to which the provisions of this Act apply by an order under this section such land shall with effect from the date on which such conversion takes effect become non-agricultural land and the non-agricultural tenant of such land shall for the purposes of this Act be deemed to have held it as such a tenancy with effect from the date on which such tenant or his predecessor-in-interest was first inducted into the land.
