§24 (1).
right or interest shall be entitled at his option either —
(i) on giving such notice as hereinafter mentioned, to an assignment of the right or the grant of a similar interest therein for the remainder of the term of the right for such consideration as, failing agreement, may be determined by arbitration; or
(ii) without any such assignment or grant, to continue to reproduce or perform the work in like manner as theretofore subject to the payment, if demanded by the author within three years after the date at which the right would have so expired, of such royalties to the author as, failing agreement, may be determined by arbitration, or, where the work is incorporated in a collective work and the owner of the right or interest is the proprietor of that collective work, without any such payment;
The notice above referred to must be given not more than one year nor less than six months before the date at which the right would have so expired, and must be sent by registered post to the author, or, if he cannot with reasonable diligence be found, advertised in the London Gazette and in two London newspapers:
