Provided that where a firm, association or company has given notices in writing to the Chief Inspector and the Inspector of the port where any dock work is being carried that it has nominated,-

(a) in the case of a firm, any of its partners;

(b) in the case of an association, any of its members;

(c) in the case of a company, any of its directors, who is resident, in each case in any place to which this Act extends and who is in each case either in fact in charge of the management of, or holds the largest number of shares in, such firm, association or company, to assume the responsibility of the person in charge of any dock work for the purposes of this Act, such partner, member or director, as the case may be, shall, so long as he continues to so reside and be in charge or hold the largest number of shares as aforesaid, be deemed to be the person in charge of such dock work for the purposes of this Act unless a notice in writing cancelling his nomination or stating that he has ceased to be a partner, member or director, as the case may be, is received by the Chief Inspector.