4The power to revoke or vary a licence under section 24 of the principal Act granted before the coming into operation of section 41(1) of this Act shall be exercisable by the local education authority in whose area the place where the person to whom the licence relates is to be trained in accordance with the licence is situated, or if more' than one such place is specified in the licence, the local education authority for the area where the place first so specified is situated.