On an historic evening for gay rights, an overwhelming majority of MPs, 400 to 175 voted in favour of the Marriage (Same Sex Couples) Bill – a vote made perhaps even more symbolic given it occurred under a Conservative led government.
The prime minister, who did not attend the debate despite being the driving force behind the Bill, said in a statement that allowing gay people to marry would "make our society stronger".
However despite Cameron's strong backing, only 127 of 303 Tory MPs voted in favour. After a seven-hour debate, 136 Conservative voted against allowing gay people to wed and a further 40 abstained.
Among the dissenters were Northern Ireland secretary Owen Paterson and Welsh secretary David Jones.
And significantly the attorney general, Dominic Grieve, who was present on the front bench for much of the debate, decided to abstain. As did defence secretary Philip Hammond, who had been an outspoken critic of same-sex marriage in recent weeks.
Several junior ministers in Cameron’s government also took advantage of the free vote to register their disagreement with gay marriage without fear of formal punishment, including transport minister Simon Burns, energy minister John Hayes, and Europe minister David Lidington.
Despite being in the minority across the Commons, many Tory MPs who opposed the Bill appeared triumphant in defeat and appeared to welcome the split in their own party.
Stewart Jackson, the Peterborough MP who warned during the debate that gay marriage would open a “Pandora’s box” and threaten religious freedom, said Cameron’s authority had been fatally undermined.
“The only comparable rebellion is the Iraq war vote in 2003 which undermined Blair's Premiership. Tonight's vote will do the same for Cameron” he said after the vote.
Most of the high profile dissenters, including Grieve and Hammond did so in silence, voting with their feet in the lobbies rather than with their voices in the debate – unlike many backbenchers who were unrelenting in their criticisms.
North Thanet MP Roger Gale said for the coalition to attempt to introduce gay marriage was "Alice in Wonderland territory" and "Orwellian".
Former defence minister Sir Gerald Howarth said it was “simply wrong" and attacked the "equality mantra" behind the Bill. "It has caused deep and needless divisions within the Conservative Party. There is no mandate for it," he said
And Gainsborough MP Edward Leigh, much to the confusion of many, said he feared the "merciless prism of equality" that was behind the Bill.
"We should be concerned with equality, but not at the expense of every other consideration, not at the expense of tradition,” he said.
Many Conservative MPs gave impassioned speeches in favour of gay marriage, including former police minister Nick Herbert who said millions of people were watching the debate. "I know that the signal we send today about whether the law fully recognises the place of gay people in our society will really matter,” he said.
"Above all, I think of two people, faithful and loving, who simply want their commitment to be recognised, as it is for straight couples, and that in the end is what this bill is about."
And Totnes MP Sarah Wollaston said a vote for gay marriage was a “vote for love and equality".
However in the immediate aftermath of the vote the voices of pro-gay marriage Conservatives were not loud enough to disguise the obvious split in the party and the fact the prime minister was unable to convince the majority of his own MPs to follow him through the ‘aye’ lobby.
Cameron acknowledged the split in his party after the vote with a message posted on Twitter.
Allowing gay people to wed is a key plank of Cameron's modernising agenda designed to distance his party from its past, including its implementation of the Section 28 law introduced in the 1980s that banned the "promotion" of homosexuality in schools.
The prime minister will hope that once the dust settles on Tuesday's debate his legacy as the Tory prime minister who introduced gay marriage will resonate more than the protests from half his parliamentary party who vocally opposed it.
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