What doctrine is embodied in section 43 of the Transfer of Property Act, 1882?

Section 43 concerns a later-acquired interest of someone who purported to transfer property. Its operative doctrine is feeding the grant by estoppel.

Buyer beware is a different principle. Section 43 allows the transferee to elect to take the later-acquired interest in the stated circumstances.

Feeding the grant by estoppel applies when a person who fraudulently or erroneously represented authority purported to transfer immovable property for consideration and later acquired an interest. The transferee may elect to take the interest while the contract subsists, subject to the statutory third-party protection.

Part performance concerns section 53A. Section 43 instead addresses the effect of a later acquisition of interest by the transferor.