Gay marriage legislation has been approved after a backbench bid to derail it failed.

Only 70 MPs – half the number predicted – supported an amendment by East Worthing and Shoreham MP Tim Loughton to extend civil partnerships to heterosexual couples.

But the move, which Brighton Pavilion MP Caroline Lucas blasted as “playing political games” with equality, was easily defeated in a free vote by a large majority of 370.

An embarrassing reverse was avoided after the Government accepted Labour calls for an immediate review of civil partnerships instead.

But, as it passed through the final stages in the Commons last night, Mr Loughton accused ministers of doing a “grubby deal” with Labour and said the battle would continue in the upper chamber.

Speaking in the Commons on Monday, Mr Loughton said: “If the Bill goes through in its current form, an inequality will be created and there will be a delay – we do not know for how long – for opposite-sex couples, who are unable to access civil partnerships, with no commitment that it will be addressed, while same-sex partners will be able to access marriages in fairly short order.”

Wealden MP Charles Hendry and Crawley MP Henry Smith were the only other Sussex MPs to back Mr Loughton’s bid.

But Nick Herbert, the MP for Arundel and South Downs, claimed a number of Tory MPs were supporting the amendment as they wanted to halt the bill.

Mr Herbert said: “Some members are breathing the word ‘equality’ for the first time.

“It sticks in the craw of many of us to be lectured suddenly now about equality by members who have been opposing this bill and equality and every single measure that has come forward to promote equality in the first place, including civil partnerships.”

Green MP Dr Lucas said: “This is a question of equal love. It is not about asking for special treatment for gay couples or straight couples; it is about everyone enjoying the same rights regardless of their sexuality.”

Speaking after the debate, Tory MP Sir Peter Bottomley said he believed the fact fewer people voted for the amendments than against the legislation in an initial Commons vote showed a growing support for the view that gay marriage was “fair and right”.

The Worthing West MP said: “I predict that in ten years' time people will look back and wonder why they were against it for so long.”

The vote on the third reading took place last night.

Mr Loughton and Mr Smith were among 128 Tories that voted against the bill.

In total, it was voted through by 366 to 161.