Any of the powers of the administrative trustees may be exercised at a duly convened meeting of the trustees at which two or more of the trustees are present notwithstanding that one or more of the trustees are not present at the meeting or that the decision to exercise the power is taken by those present and voting or a majority of them and that one or more of the administrative trustees do not concur therein provided that in relation to the power conferred by clause 8e hereof this clause shall have effect subject to the proviso to that clause.