Section 3A. Any recordable instrument purporting to affect an interest in real estate, title to which is held by a city, town, district or regional school district, executed in the name of a town by its selectmen, in the name of a city by its mayor or by its city manager in the case of a city having a Plan D or Plan E charter, or in the name of a district or regional school district by the chairman of its prudential committee or other governing board or by any agent or committee authorized by particular vote of the city, town or district or in the case of a municipality acting by or through an industrial development financing authority as provided in section seven of chapter forty D by vote of the board of directors of said authority, shall be binding on the city, town, district or regional school district in favor of a purchaser or other person relying in good faith on such instrument notwithstanding inconsistent provisions of general or special law, the city or town charter, by-laws, resolutions or votes.