Prime minister David Cameron is ‘emphatically’ in favour of allowing gay couples to marry, PinkNews.co.uk has been told.

A senior Downing Street source said Mr Cameron had “personally intervened” to ensure that a consultation on the issue takes place and that the law is changed within the lifetime of this parliament.

The source added that the prime minister believes gay civil marriage “is the right thing to go for”.

In 2006, in his first speech as Conservative Party leader, he said: “There’s something special about marriage. It’s not about religion. It’s not about morality. It’s about commitment [...] And by the way, it means something whether you’re a man and a woman, a woman and a woman or a man and another man.”

Mr Cameron elaborated on this in a question and answer session with PinkNews.co.uk readers during last year’s general election campaign.

Asked if he’d support a move to full marriage, Mr Cameron wrote: “I am so glad that we now have civil partnerships. They have helped remove discrimination and have given gay people the rights that they deserve. I want to do everything I can to support commitment and I’m open to changing things further to guarantee equality.”

The deputy prime minister and leader of the Liberal Democrats Nick Clegg first announced his support for gay marriage in a similar session with PinkNews.co.uk readers. He wrote: “I support gay marriage. Love is the same, straight or gay, so the civil institution should be the same, too. All couples should be able to make that commitment to one another.”

Similarly, during the Labour leadership campaign, Ed Miliband used a comment article for PinkNews.co.uk to declare his support for the issue. He wrote: “‘Separate but equal’ is not good enough and PinkNews.co.uk’s own recent poll demonstrated the huge support in the LGBT community for a right to marry. I want to see heterosexual and same-sex partnerships put on an equal basis and a Labour Party that I lead will campaign to make gay marriage happen.”

Mr Cameron is understood to be confident of pushing through the changes before 2015, despite the inevitable religious and traditionalist backlash.

The Scottish government recently announced a consultation on the issue and deputy first minister Nicola Sturgeon said ministers were minded towards marriage equality.

The announcement sparked a furious reaction from Catholic Church leaders who claimed that the SNP would lose the support of 800,000 Catholics.

Bishop of Paisley Philip Tartaglia, who is expected to become the next Archbishop of Glasgow, said marriage equality would be “an act of cultural vandalism”.

Church leader Cardinal Keith O’Brien called the proposals a “grotesque subversion of a universally accepted human right” and said that gay parents cannot adequately bring up a child.