MPs will vote tonight on historic proposals to legalise gay marriage amid intense and sometimes vitriolic lobbying on both sides of the debate.
Most pressure is on around eighty Tory MPs who have yet to declare which way they will vote and whose decision will ultimately determine whether David Cameron gets the symbolic backing of a majority of party for the proposal.
Labour are expecting the vast majority of their Parliamentary Party to back the move which will easily pass along with the backing of the Liberal Democrats.
David Cameron said today that allowing gay people to marry will "make our society stronger."
"Today is an important day. I am a strong believer in marriage. It helps people commit to each other and I think it is right that gay people should be able to get married too," he said.
"This is, yes, about equality. But it is also about making our society stronger.
"I know there are strong views on both side of the argument - I accept that. But I think this is an important step forward for our country."
Mr Cameron was speaking as a stormy debate on the second reading of the Marriage (Same Sex Couples) Bill drew to its conclusion in the House of Commons.
Introducing the Bill, Culture Secretary Maria Miller insisted that it would make Britain "a fairer place to live".
Last night, in an unprecedented joint letter, the three most senior Secretaries of State wrote that gay marriage was “the right thing to do at the right time”.
“Civil partnerships for gay couples were a great step forward, but the question now is whether it is any longer acceptable to exclude people from marriage simply because they love someone of the same sex,” wrote George Osborne, William Hague and Theresa May.
Their intervention represents a last attempt to persuade wavering Conservatives to drop their deep-seated opposition to legalising gay marriage. To further encourage doubters it was announced that Iain Duncan Smith, a cabinet known to have doubts about the proposals will vote with the Government.
With emotions running high on both sides of the debate, religious opponents of gay marriage were accused of subjecting undecided MPs to “vitriolic abuse”.
One MP told The Independent that a number of his colleagues were intending to vote for the Gay Marriage Bill because of the “appalling” nature of the emails they had received.
Meanwhile the gay Conservative MP Conor Burns, who has not publicly stated how he will vote, complained that he had been attacked from both the gay and Christian communities. “The whole thing is deeply unpleasant and people are saying things that you wouldn’t say to people you despised or hated,” he said. “I don’t know what kind of God some of those people who have contacted me from religious groups believe in – but he’s certainly not compassionate or loving.”
The MP, who asked not to be named said: “Quite a few of us who were considering abstaining will vote in favour of gay marriage because of the unreasonable nature of the emails we have been receiving. Some of the emails I’ve had are simply appalling and I’m fed up with it.”
The Conservative MP Angie Bray, who has also not stated which way she will vote, said she had been sent unpleasant emails from both sides. “You get emails from one side saying you’re morally deficient if you vote no and emails threatening hell fire and brimstone if you vote yes. It has frankly been an ill-tempered debate on both sides.”
Campaigners calculate that, of the 303 Conservative MPs, 114 are likely to vote against the proposal and 108 in favour. The pressure is greatest on the 81 MPs thought to be either neutral or undecided, with their votes set to determine whether Mr Cameron can claim the backing of a majority of his parliamentary party.
David Burrowes, the main opponent of the Gay Marriage Bill said the abuse was just as strong from those in favour.
“I’ve had death threats, hostility and hate mail,” he said. “My children have even been told that their dad is a homophobe. There has been abuse and intolerance of both sides.”
Downing Street has attempted to calm the waters. Mr Cameron has deliberately chosen not to make any statement ahead of today’s debate while officials have made clear there will be no recriminations against those who vote no.
Meanwhile a survey for The Independent has found that a large proportion of the 38 Conservative MPs who opposed the introduction of civil partnerships now support the 2004 change. This will bolster those who claim Tory opposition to gay marriage will also evaporate once the measure has been passed.
The MPs who have changed their views on civil partnerships include Owen Paterson, now the Environment Secretary, who has said he now believes the measure “advanced equality”. However he still intends to vote against gay marriage.
Another minister Andrew Robathan, who also opposed civil partnerships, said, “I have come round to civil partnerships because it has made a lot of people contented and I am quite keen on people being contented.” The Conservative MP Roger Gale added: “With hindsight it was a reasonable bit of legislation. But as it happening I was right to be concerned that it was the thin end of the wedge.”