At this week’s Tory conference, Chancellor George Osborne told delegates that equal marriage “is a very powerful part of the Conservative story”.

It’s been revealed after Monday’s conference speech, where he briefly touched upon same-sex marriage as an example of a policy “delivered by Conservatives in government”, the Chancellor elaborated on this theme at a Channel 4 event attended by Tory activists.

He said: “A landmark piece of social legislation has been passed this year – it is not universally popular in this room probably.

“But gay marriage is a very big piece of social legislation. There is a Conservative story which is not told often enough.

“Of William Wilberforce, being the man who freed the slaves, of Shaftsbury, who said we will limit factory hours and we are not going to let children work down the mines.”

“That is a very powerful part of the Conservative story and it is a part that I am very happy to associate myself with.”

Yesterday, Downing Street denied claims made in the Daily Mail that Prime Minister David Cameron told senior Tory activists at a private meeting that he made a “terrible” mistake over equal marriage.

On Wednesday, Mr Cameron listed Britain’s acceptance of people who are gay as one of many reasons to be proud of the country in his keynote speech at the Conservative Party Conference in Manchester – although he failed to mention equal marriage.

Claims that he had privately regretted the policy were first made public last weekend by the journalist Matthew d’Ancona, in his new book about the Coalition, “In It Together”.

The Prime Minister firmly rejected the allegations soon after in a BBC interview. Mr Cameron said: “I don’t regret it. Britain is a more equal and fairer country for having done it.

“It’s certainly true to say that this is an important change. I don’t think I expected quite the furore that there was.

“It’s clearly been very difficult for some people to take on, and I completely understand and respect that.

“I’m not sure perhaps at the beginning we got across to people that this was about marriages that could take place in register offices, that this was not going to change what happened in church, mosques or synagogues.”

He continued: “I am passionate about marriage. I think it’s a great institution, and I think it should be available to people who are gay as well as those of us who aren’t.”