155.—(1) This Article applies where—
(a)a woman has been employed on like work with a man in the same employment,
(b)a woman has been employed on work rated as equivalent with that of a man in the same employment, or
(c)a woman has been employed on work which, not being work in relation to which sub-paragraph (a) or (b) applies, was, in terms of the demands made on her (for instance under such headings as effort, skill and decision), of equal value to that of a man in the same employment,
and service in that employment was pensionable service under an occupational pension scheme.
(2) If, apart from this paragraph, any of the payment functions so far as it relates (directly or indirectly) to that pensionable service —
(a)is or becomes less favourable to the woman than it is to the man, or
(b)is or becomes less favourable to the man than it is to the woman,
that function has effect with such modifications as are necessary to ensure that the provision is not less favourable.
(3) Paragraph (2) does not operate in relation to any difference as between a woman and a man in the operation of any of the payment functions if the Board proves that the difference is genuinely due to a material factor which—
(a)is not the difference of sex, but
(b)is a material difference between the woman’s case and the man’s case.
(4) Paragraph (2) does not apply in such circumstances as may be prescribed.
(5) This Article has effect in relation to the exercise of any payment function in so far as it relates (directly or indirectly) to any pensionable service on or after 17th May 1990.
(6) In this Article—
“payment function” means any function conferred on the Board by or by virtue of this Chapter which relates to a person’s entitlement to or the payment of any amount under or by virtue of—
the pension compensation provisions,
Article 150 (duty to pay scheme benefits unpaid at assessment date etc.),
Article 153 (discharge of liabilities in respect of compensation), or
Article 154 (discharge of liabilities in respect of money purchase benefits);
“pensionable service” has the meaning given by Article 121(1) of the 1995 Order.