A committee appointed by a county council or local authority for any of the purposes of this Act may, subject to any directions of the council or authority, appoint such and so many sub-committees consisting either wholly or partly of members of the committee as the committee think fit and, subject as aforesaid, may delegate, with or without restrictions or conditions, any of their functions to a sub-committee so appointed :

Provided that a majority of the members of any such sub-committee shall be members of the county council or, as the case may be, of the local authority.