The Secretary of State or Defence Council shall not make, or recommend to Her Majesty the making of, any instrument relating to the terms and conditions of service of members of the naval military or air forces of the Crown . . . , if the instrument has the effect of making a distinction, as regards pay, allowances or leave, between men and women who are members of those forces . . . , not being a distinction fairly attributable to differences between the obligations undertaken by men and those undertaken by women as such members as aforesaid.
The Secretary of State or Defence Council may refer to the Central Arbitration Committee for their advice any question whether a provision made or proposed to be made by any such instrument as is referred to in subsection (1) above ought to be regarded for purposes of this section as making a distinction not permitted by that subsection.