Story highlights Landmark ruling a "huge step for LGBT couples," retiree says

The decision could be overruled after Brexit

(CNN) The UK Supreme Court ruled on Wednesday that employers must give same-sex couples the same rights to a spouse's pension as straight couples.

The landmark decision follows the case of British retiree John Walker, 66, who launched a five-year legal battle against former employer Innospec after being told that if he died, his husband would receive a pension of only a few hundred pounds a year. If Walker had been married to a woman however, she would receive £45,000 (about $58,000) annually for life.

John Walker and his then partner at their civil partnership ceremony in 2006. This image, obtained by CNN, was originally blurred by Walker in order to protect the identity of his husband.

Walker had worked at the multinational chemicals company for more than 20 years and had made mandatory pension scheme contributions like the rest of the company's employees.

After retiring in 2003, Walker and his partner entered a civil partnership in 2006 -- which they later registered as a marriage.

When Walker went to the pensions department to inform them of the change to his paperwork, he was told his partner wouldn't be entitled to the same financial protections as a heterosexual spouse.

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