Margot James, the first openly lesbian Conservative Member of Parliament, spoke out in favor of the bill.

In its "second reading" on February 5, 2013, U.K.'s House of Commons voted overwhelmingly in favor of marriage equality. Following six hours of intense debate, the Commons voted 400 to 175 in favor of the coalition government's plan to permit same-sex marriage. The bill enables same-sex couples to be married in both civil and religious ceremonies, where a religious institution had formally consented, in England and Wales. It also allows couples who have previously entered into civil partnerships to convert their relationship into a marriage.

The bill, which was formally introduced on January 24, 2013 is the result of a long period of consultation. The consultation received a record 228,000 responses, a healthy majority of which were in favor of marriage equality.

Despite a fierce campaign mounted by the Church of England and the Roman Catholic Church, polls show a majority of Britons in favor of marriage equality.

While the bill allows gay and lesbian couples to marry in civil ceremonies and also permits religious organizations that decide to "opt in" to conduct marriage ceremonies for gay and lesbian couples, it also contains a "quadruple lock" of measures designed to protect religions that do not choose to "opt in" from being challenged in domestic or European courts.

Religious organizations and individual ministers are prohibited from marrying same-sex couples unless their respective governing bodies have expressly opted in to do so.

Following its approval on February 5, the bill will now be subjected to the scrutiny of an MP's committee before making its way back to the Commons for a third reading--at which point it will be referred to the House of Lords.

The overwhelming vote in favor of the bill makes it likely that it will be approved by the House of Lords, though the government has refused to rule out using the Parliament Act to override the House of Lords in the event the bill becomes stalled in that body.

Conservative Prime Minister David Cameron described the vote as "an important step forward for our country."

Liberal Democratic Deputy Prime Minister Nick Clegg hailed the vote as "a landmark for equality in Britain. . . . No matter who you are and who you love, we are all equal. Marriage is about love and commitment, and it should no longer be denied to people just because they are gay. The Liberal Democrats have long fought for equal marriage. It is party policy and I am proud that the Liberal Democrats are part of the coalition government that are making it happen."

Labour Party leader Ed Milliband said "This is a proud day and an important step forward in the fight for equality in Britain. The overwhelming majority of Labour MPs supported this change to make sure marriage reflects the value we place on long-term, loving relationships whoever you love. Equal marriage builds on Labour's successes in government which include the repeal of Section 28, equalising the age of consent, the introduction of civil partnerships and changes to the rules governing adoption."

It should be noted that 144 Conservative MPs voted against the marriage equality bill, while only 136 voted for it. In contrast, 217 Labour MPs voted in favor of the bill, while only 22 voted against it. Among Liberal Democrats, who are in coalition with the Conservatives, 44 voted in favor and 4 voted against. Hence, the passage of the marriage equality bill depended on the strong support of the coalition partner Liberal Democrats and the opposition Labour Party.

Ben Summerskill, Chief Executive of the gay rights group Stonewall, praised the House of Commons: "As the last piece of the legislative jigsaw providing equality for gay people in Britain, this is a truly historic step forward. We're absolutely delighted that MPs have demonstrated so overwhelmingly that they're in touch with the twenty-first century."

Among many outstanding speeches in favor of the bill was that of Margot James, who in 2010 became the first Conservative lesbian in Parliament. She responded to MPs who opposed the bill by arguing that equality did not mean getting rid of differences: "We are different, and we should celebrate differences. I agree with that, we should celebrate cultural and other differences, but having been different for most of my life I can assure you being treated equal would be very welcome indeed."

In another moving speech, captured in the video below, Conservative MP Mike Freer also criticized the rhetoric of those opposed to same-sex marriage and spoke feelingly of his relationship with his partner of 21 years. He told his colleagues, "I'm not asking for special treatment I am simply asking for equal treatment."

Another openly gay Conservative MP, Nick Herbert, also spoke forcefully in favor of marriage equality.

In the video below, from 2010, Margot James assures young people that "It Gets Better."

Below is a video clip of Cameron's speech at the Conservative Party conference in Manchester on October 5, 2011 in which he declared his support of same-sex marriage as a conservative principle.