A gay man has won a landmark pensions battle at the UK's highest court which could provide financial security for thousands of same-sex couples.
Ex-cavalry officer John Walker, 66, said he was "thrilled" after Supreme Court justices ruled unanimously in his favour in his long-running action to secure his husband the same rights a wife would have in the event of his death.
Mr Walker retired from chemicals group Innospec Ltd in 2003 after working for the company for more than 20 years - he had made the same contributions to the pension scheme as his heterosexual colleagues.
His legal challenge centred on an exemption in the 2010 Equality Act allowing employers to exclude same-sex partners from spousal benefits paid into a pension fund before December 2005, which was when civil partnerships became legal.
On Wednesday a panel of five justices, headed by the Supreme Court's deputy president Lady Hale, made a declaration that the exemption was "incompatible with EU law and must be disapplied".
The decision means Mr Walker's husband, a former computer executive in his fifties who prefers not to be named, will be entitled on his death - provided they are still married - to a spouse's pension of around £45,000 a year, rather than about £1,000 which he would have received.
The couple have been together since 1993, entering into a civil partnership in January 2006, which was later converted into a marriage.
After the ruling, Mr Walker and human rights organisation Liberty, which represented him, urged the Government to promise there would be no "rollback" on LGBT rights after Brexit.
Mr Walker said: "I am absolutely thrilled at today's ruling, which is a victory for basic fairness and decency.
"Finally this absurd injustice has been consigned to the history books – and my husband and I can now get on with enjoying the rest of our lives together.
"But it is to our Government's great shame that it has taken so many years, huge amounts of taxpayers' money and the UK's highest court to drag them into the 21st century."
He said: "What I would like from Theresa May and her ministers today is a formal commitment that this change will stay on the statute books after Brexit."
Liberty said the ruling could change the lives of thousands of couples and would mean any company using the Equality Act to exclude same-sex partners from pension benefits in the same way would now be breaking the law.
Lawyer Emma Norton said: "This ruling was made under EU law and is a direct consequence of the rights protection the EU gives us.
"We now risk losing that protection. The Government must promise that there will be no rollback on LGBT rights after Brexit – and commit to fully protecting them in UK law.
"How else can John be sure he and others like him have achieved lasting justice today?"
During the Supreme Court hearing of the case in March, a QC for the Work and Pensions Secretary pointed out that the costs involved in "requiring all pension schemes to equalise entitlements retrospectively" would be £100 million for private sector schemes and a further £20 million for public sector schemes.
A Government spokesman said: "We are reviewing the implications of this judgment in detail and will respond in due course.
"The rights of same-sex couples have been transformed for the better since 2010, including the introduction of same-sex marriage and legislation to ensure that pensions are built up equally for all legal partnerships."