Part performance protection bars a transferor from enforcing rights against a possessor who has performed or is willing to perform under a written transfer contract. Section 53A protects a transferee who, under a written and signed contract for sale of immovable property, has taken or continued possession or done acts in furtherance of the contract and has performed or is willing to perform; in such cases the transferor and successors are barred from enforcing rights against the transferee regarding the possessed portion, except rights expressly in the contract, while a bona fide purchaser for consideration without notice remains unaffected.