William Hague, the foreign secretary, who as Conservative leader opposed the abolition of Section 28 has confirmed that he will vote in favour of same-sex marriage.

In the 1999, Mr Hague opposed the repeal of Section 28, a law that prevented the ‘promotion’ of homosexuality in schools and imposed a three-line whip on his MPs to vote against the repeal.

However, in 1994, he did back a failed attempt to equalise the age of consent that was opposed by many Conservatives and during his election campaign to be Conservative leader, he hinted that he would support marriage for gay couples. In 2005, he voted for the introduction of civil partnerships.

Today, speaking to the BBC he said that same-sex marriage “is an issue that’s here all around the Western world. This is an issue in France, in the united states. If we weren’t debating it now it would be a big issue in the next general election and we’d all have to say where we stood then.

“I think as times have changed, civil partnerships came in… Within a remarkably short period of time, those things become accepted. I think the same will happen with this.

“I look at three things.

“Is it right in principle? And I think it is. Marriage is a very positive institution in our society and we shouldn’t deny it to people on a discriminatory basis.

“Is there sufficient public consent for it to be a law. Yes there is .

“Are the sufficient protections for those who disagree with it for their own religious principles? Yes there is. Churches and faith groups that don’t want to have same-sex marriages don’t have to do them.

“On that basis we can vote for this.”

Earlier today, a collection of current or past chairmen of local Conservative Party Associations delivered a letter to David Cameron by hand where they plead for him not to go ahead with Tuesday’s vote on same-sex marriage.