Section 23, we have seen, provides for exemption from the operation of all or any of the provi sions of the Act or any scheme made thereunder of "all or any class or classes of Security Guards employed in any factory or establishment or in any class or classes of factories or establishments." The basic condition to be satisfied is that the State Government should be of the opinion that "all such Security Guards or such class or classes of Security Guards are in the enjoyment of benefits, which are on the whole not less 30 favourable to such Security Guards than the benefits provid ed by or under this Act or any Scheme made thereunder. "A close scrutiny of section 23, particularly in the light of section 1(4) read with the definition of 'Security Guard ', makes it clear that the exemption is not in respect of an agency or an agent or even a factory or establishment but in respect of all or any class or classes of Security Guards employed in any factory or establishment or in any class or classes of factories or establishments.