Five judges at the Supreme Court, Britain's highest court, ruled that if John Walker died, his husband would be entitled to a spouse's pension, provided they stay married.
The 66-year-old launched a discrimination lawsuit when the company he worked for said it would not pay out spouse benefits because his pension plan predated 2005, when gay civil partnerships became legally recognized.
The Court of Appeal ruled against Walker in 2015, but the Supreme Court overturned that decision Wednesday. The decision means that Walker's partner will be entitled to spousal benefits of around 45,000 pounds ($57,800) a year instead of about 1,000 pounds a year.