under section 307, after the end of the period of 42 days beginning with the day on which it first came to the knowledge of the trustee that property in question had been acquired by, or had devolved upon, the bankrupt;

under section 308 F1or section 308A, after the end of the period of 42 days beginning with the day on which the property F2or tenancy in question first came to the knowledge of the trustee.

any thing which comes to the knowledge of the trustee is deemed in relation to any successor of his as trustee to have come to the knowledge of the sucessor at the same time; and

any thing which comes (otherwise than under paragraph (a)) to the knowledge of a person before he is the trustee is deemed to come to his knowledge on his appointment taking effect or, in the case of the official receiver, on his becoming trustee.