In an apparent volte face on “full commitment” to equal marriage, No. 10 announced today that Conservative MPs will be given a free vote on voting for the measure in Parliament, though it has denied that it is backtracking on its support for the measure.

The Prime Minister, David Cameron, has lent his personal support to extend marriages to same-sex couples, and the measure has the firm backing of the Lib Dem leader Nick Clegg and the Labour leader Ed Miliband.

Just yesterday, a spokesperson for Downing Street said that the plans were a “government commitment,” which many interpreted as a signal that all ministers were expected to support the measure. However, early this morning, the BBC obtained a statement from No. 10 to the effect that it was an issue of conscience, “like abortion,” and therefore ministers would be given a free vote on the issue.

While the source confirmed that the government was still confident of passing the legislation, what prompted this overnight shift in position remains unclear.

However, an increasing number of socially conservative Tory ministers have spoken out against the measure, including Secretary of State for Northern Ireland, Owen Paterson, and Children’s Minister Tim Loughton. The Defence Secretary, Philip Hammond had also said that equal marriage was not a priority, a comment that George Osborne echoed in an interview with Andrew Marr.

Last night, in an interview with the Daily Telegraph, which with its sister publication, has campaigned vigorously against the measure, the defence minister Gerald Howarth welcomed the shift in position, saying it was “absolutely right and proper” that ministers vote against the proposals if they wanted. Mr Howarth had suggested that the Tory losses in local election was actually due to plans for equal marriage, something that Foreign Secretary William Hague was quick to dismiss.

Meanwhile, Nick Clegg, signing up to the Coalition for Equal Marriage (C4EM), has warned the Tories against backing down on the measure, saying Lib Dems and the Coalition were committed to see the measure through before the next general election.

Just yesterday, two Tory MPs, the Justice Minister Crispin Blunt, and the PM’s Parliamentary Private Secretary, Desmond Swayne, recorded messages of support for the @Out4Marriage campaign.

Update: The Out4Marriage campaign is filming a video with a senior cabinet minister today, and PinkNews.co.uk expects to publish the video shortly.