The court ruled that same-sex partnerships must be fairly and properly recognised within UK pension schemes and treated the same as if they had an opposite sex partner. 

Former pensions minister Baroness Altmann said: “At last, there is clarity that pension schemes cannot discriminate on gender grounds in this way."

She said: "There could be further implications of this ruling, in that widow's pension rights in many schemes differ from the pension rights of widowers. In some schemes, a husband cannot inherit the wife's pension, but a wife will inherit that of her deceased husband. I expect this issue will now be looked at again - and the cost to public sector pension schemes could be hundreds of millions of pounds.

“Estimates suggest that the cost to private sector pension schemes could be around £100million and there will also be costs for public sector pension schemes too.

“Of course we will not know the precise costs because the money only needs to be paid once the member passes away and only if the member is survived by their partner.”

Previously if pension scheme members had a partner of the same gender, even though they may have been together for decades, their pension scheme might refuse to pay a survivor's pension on the grounds that the law only recognised gender-equal partnerships since 2005.

Baroness Altmann said: “In reality, most pension schemes have already been treating all partnerships the same, but around 20% of private schemes have not yet done so and Mr Walker, who has lived with his partner for decades, has sued the Innospec pension scheme because it refused to agree that his partner would inherit his survivor pension rights for the entire period in which he belonged to the scheme.

“Having had to fight all the way up to the Supreme Court, the issue has been settled and all UK pension schemes will now have to pay survivors' pensions to same-sex partners on the same basis as they would for opposite sex partnerships.”