In the case of a person to whom section 23 of the Act (trade disputes) applies and for so long as it applies, any payment up to the amount of the relevant sum within the meaning of subsection 6 of that section made by a trade union; but, notwithstanding regulation 23 (calculation of income and capital of members of claimant's family and of a polyamous marriage) if this paragraph applies to a claimant it shall not apply to his partner except where, and to the extent that, the amount to be disregarded under this paragraph is less than the relevant sum.