Conservative MP Mike Freer has criticised the same-sex marriage bill for failing to address pension inequalities. He says he hopes to table an amendment changing it through an ally in the House of Lords.

The Marriage (Same Sex Couples) Bill passed its third readings in the House of Commons last week, but came under fire from some MPs due to inequalities it would create in pensions between same-sex and opposite-sex couples.

The bill would not amend inequalities which can currently occur in pension schemes for civil partners, which allow them to limit the survivor’s benefits to accrual from 2005 – the point at which civil partnerships were introduced in the UK.

Mike Freer was one of several MPs pushing for an amendment to the bill which would give married same-sex couples the same pension rights as married opposite-sex couples.

It eventually failed, largely due to objections raised by Equalities Minister Helen Grant, who said “We’re very conscious that these [pension] schemes already face difficult economic conditions.” The government estimated that the cost of equalising pensions would be £18 million.

Speaking on the BBC’s Money Box programme on Saturday, Mr Freer said: “I think that’s a bit of a red herring. In fact, I’m in a pension scheme, and I’m paying into my parliamentary pension scheme, and it takes exactly the same rate as my heterosexual colleagues. And yet, my surviving partner, if I were to die, would get a completely different pension. Why should a gay man pay in the same but get something completely different for their spouses who survive?”

“The government have said the cost will be £18 million. But in terms of the pensions industry, which has £360 billion pound assets under management, it’s a fraction – 0.006%.”

He added: “I’m hoping that when the bill goes into the Lords I’ll get a friendly Lord to table the amendment in the Lords to get another go at equal pension rights.”

During the debate he spoke of his own surprise at finding out the difference between his civil partner’s potential benefits, and those of a married couple.

“I don’t think gay people are different from any other, most people seem quite ignorant of their own pensions. I know more than most because I was in the industry for a little while,” he said.

He observed: “Some of the critics of the bill said ‘Why bother changing it if legal rights are the same between marriages and civil partnerships?’, and actually this is a stark example of why the rights between civil partners and those in marriages aren’t the same.”

Mr Freer noted that around a third of pension schemes do offer equal pensions to same-sex couples: “We think those that are in contracted-out schemes are fine, but not exclusively. It’s mainly contracted-in schemes.

“I’d urge everybody in a pension scheme to ask their pensions administrator if they can get it in writing, how they treat civil partners, because it’s murky,” he said.

Peers in the House of Lords are said to be planning a final attempt to block the equal marriage bill. It is expected that the debate in the Lords will go on into the night, or into a second day as seventy-five members have already signed up to speak in the debate.