118Restrictions on contracting out
(1)Except as provided by subsection (2) below, any provision in an agreement (whether a contract of employment or not) shall be void in so far as it purports—
(a)to exclude or limit the operation of any provision of this Act; or
(b)to preclude any person from presenting a complaint to,
or bringing any proceedings under this Act before, an industrial tribunal, or for making any reference, claim, complaint or application under this Act to the Service or the Committee.
(2)Subsection (1) above shall not apply—
(a)to any provision in a collective agreement excluding rights under section 22 above or Part IV of this Act, if an order under section 28 or, as the case may be, section 107 above is for the time being in force in respect of it;
(b)to any union membership agreement so far as it affects the rights of an employee under section 53 above in accordance with subsection (4) of that section;
(c)to any agreement to refrain from instituting or continuing any proceedings before an industrial tribunal where a conciliation officer has taken action in accordance with section 108(3) or (4) above ;
(d)to any agreement such as is referred to in section 16(7)(b) or (c), or 21(6)(b) or (c) above, or paragraph 11(6) or (c) of Schedule 11 to this Act, to the extent that it varies or supersedes an award under section 16 or 21 above, or, as the case may be, paragraph 10 of the said Schedule 11.