Image copyright Getty Images

A gay man has launched a legal bid for his husband to have the same pension rights a wife would have if he was in a heterosexual relationship.

Ex-cavalry officer John Walker launched an equal treatment case at the Court of Appeal.

His lawyers claim his husband would receive around 1% of the amount that would be paid to his spouse if he were married to a woman.

The government says "full equalisation" of pensions would cost around £3.3bn.

A spokesman for the Department for Work and Pensions said it would also have complex implications for pension schemes.

"We must consider the full impact of this issue before considering changes to legislation," he said.

Legal battle

Mr Walker retired from chemical group Innospec Ltd, where he had worked for 23 years, in 2003.

He has been in a relationship with his partner since 1983. They entered a civil partnership in 2006, which has since been converted into a marriage.

His legal action is against Innospec, which he claims fails to treat surviving same-sex spouses and civil partners as equal to surviving spouses in a heterosexual marriage.

In 2012, an Employment Tribunal in Manchester ruled Innospec's scheme contravened European laws. The company appealed, with the support of the Department for Work and Pensions.

The Employment Appeal Tribunal (EAT) ruled an exemption in the Equality Act 2010 disapplied pension rights accrued by Mr Walker before 5 December 2005 - the date when the Civil Partnership Act 2004 came into force and required benefits to be provided equally to civil partners and married couples.

The EAT said those rights did not have retrospective effect or allow inequalities in pay based on sexual orientation prior to that date to be addressed.

Mr Walker is now asking appeal judges to rule that decision was flawed and breaches his human rights.

He also contests it is contrary to EU laws setting out the framework for equal treatment in employment.