One of the arguments commonly deployed by opponents of equal marriage is that the existence of civil partnerships for same-sex couples means its introduction is unnecessary. Conservative MP Edward Leigh, for instance, has argued [2]: "Same-sex couples already have all the rights of marriage in the form of civil partnership. Why must they also have the language of marriage?" Former Tory defence minister Gerald Howarth has commented: "some of my best friends are in civil partnerships, which is fine, but I think it would be a step too far to suggest that this is marriage", while Environment Secretary Owen Paterson, who is expected to vote against equal marriage today, has said that the government is "rightly committed to advancing equality for lesbian, gay, bisexual and transgender people and has already taken action to do so by allowing those religious premises that wish to carry out civil partnerships to do so".

But what none of these three will tell you is that they all voted against civil partnerships when Labour introduced them [3] in 2004. MPs are, of course, free to change their minds and we should praise them when they do. But it's hard not to see their new-found support for civil partnerships as a cynical attempt to prevent the equalisation of marriage. Gay couples might already have a means of formalising their relationships but they wouldn't if Paterson, Leigh and Howarth had had their way in 2004. So, for the record, here are the 38 Conservative MPs who voted against civil partnerships, including two serving cabinet ministers (Paterson and Transport Secretary Patrick McLoughlin) and the two Labour MPs who did. Seventeen have since resigned or lost their seats.

Conservative MPs who voted against civil partnerships

David Amess (Southend West)

James Arbuthnot (North East Hampshire)

Paul Beresford (Mole Valley)

Julian Brazier (Canterbury)

Christopher Chope (Christchurch)

Patrick Cormack (South Staffordshire. Stood down in 2010)

Quentin Davis (Grantham and Stamford. Defected to Labour in 2007 and stood down in 2010)

Adrian Flook (Taunton. Stood down in 2010)

Mark Francois (Rayleigh and Wickford)

Roger Gale (North Thanet)

John Gummer (Suffolk Coastal. Stood down in 2010)

Nick Hawkins (Surrey Heath. Stood down in 2005)

John Hayes (Current energy minister and MP for South Holland the Deepings)

Mark Hoban (Current employment minister and MP for Fareham)

Gerald Howarth (Aldershot)

Greg Knight (East Yorkshire)

Edward Leigh (Gainsborough)

Peter Lilley (Hitchin and Harpenden)

Brian Mawhinney (North West Cambridgeshire. Stood down in 2005)

Anne McIntosh (Vale of York)

Patrick McLoughlin (Current Transport Secretary and MP for Derbyshire Dales)

Owen Paterson (Current Environment Secretary and MP for North Shropshire)

Andrew Robathan (Current armed forces minister and MP for South Leicestershire)

Laurence Robertson (Tewkesbury)

Andrew Rosindell (Romford)

Michael Spicer (West Worcestershire. Stood down in 2010)

Bob Spink (Castle Point. Defected to UKIP in 2008 and lost his seat in 2010)

Desmond Swayne (New Forest West)

John Taylor (Solihull. Lost his seat in 2005)

Michael Trend (Windsor. Stood down in 2005)

Andrew Turner (Isle of Wight)

Nigel Waterson (Eastbourne. Lost his seat in 2010)

Angela Watkinson (Upminster)

Ann Widdecombe (Maidstone and The Weald. Stood down in 2010)

John Wilkinson (Ruislip-Northwood. Stood down in 2005)

David Wilshire (Spelthorne. Stood down in 2010)

Ann Winterton (Congleton. Stood down in 2010)

Nicholas Winterton (Macclesfield. Stood down in 2010)

Labour MPs who voted against civil partnerships

Denzil Davies (Llanelli. Stood down in 2005)

Jim Dobbin (Heywood and Middleton)