27A. Subject to the provisions of this Chapter, where a contract to lease immoveable property is made in writing signed by the parties thereto or on their behalf, either party may, notwithstanding that the contract, though required to be registered, has not been registered, sue the other for specific performance of the contract if,-(a) where specific performance is claimed by the lessor, he has delivered possession of the property to the lessee in part performance of the contract; and (b) where specific performance is claimed by the lessee, he has, in part performance of the contract, taken possession of the property, or, being already in possession, continues in possession in part performance of the contract, and has done some act in furtherance of the contract: Provided that nothing in this section shall affect the rights of a transferee for consideration who has no notice of the contract or of the part performance thereof. This section applies to contracts to lease executed after the first day of April, 1930.