Nine years ago, in the Civil Partnership Act 2004, the New Labour government created landmark legislation recognising same sex marriages in civil and legal terms.
There are only a few small changes in the rights++ proposed by the new bill - which still requires line by line reading and a vote in the House of Lords before it becomes law - but there are two huge symbolic differences.
The first is that it allows religious institutions to recognise gay marriage...
The second cultural shift is that 'Marriage (Same Sex Couples) Bill' was introduced by the Conservative leadership....
I then write about how senior conservatives in the coalition cabinet backed the prime minister, with William Hague, the foreign secretary, George Osborne, the chancellor, and Theresa May expressing open support for the bill before the debate even began.
"Marriage has evolved over time," they wrote in a joint letter to the Daily Telegraph . "We believe that opening it up to same-sex couples will strengthen, not weaken, the institution. As David Cameron has said, we should support gay marriage not in spite of being Conservatives, but because we are Conservatives."
I then explain how the co-option of gay rights as a Conservative cause is not an entirely new phenomenon. Cameron himself has long been a moderniser in this cause, and was one of just 29 MPs to back gay adoption legislation in 2007. Before she had to trim to the right on social matters, the great icon of British conservatism, Margaret Thatcher, voted for the decriminalisation of homosexuality in 1967.
To Damian Barr, a journalist and author of the forthcoming book about Thatcher's impact on a gay young man growing up in the '80s and '90s, Maggie & Me, the success of same sex marriage bill "is actually a profoundly conservative moment." "Thatcher believed in including more and more people in traditional institutions," he told the Daily Beast. "Support for equal rights actually underpins the institution of marriage," he said: "It's part of the Thatcherite vein to include more and more people in bigger institutions that underpin the social fabric and collective narrative. "
The article then goes onto explore, given the close relation between Thatcher and Reagan and conservative policies on both sides of the Atlantic, such a shift is possible on the right of US politics. One salient difference between the US and UK is the level of religious observance. The 2011 UK census showed 25 per cent of the population describing themselves as 'atheists' and only 57 per cent calling themselves 'Christian' compared with 6 per cent non-believers and 73 per cent Christian in a recent Pew Poll of the US.
But religion doesn't explain everthing. Secular France is having a horrendous debate on the issue, with only two MPs from the majority right wing opposition party, the UMP, support the marriage equality bill now before the National Assembly. However, Catholic Spain and Portugal voted for equality in 2005 and 2010 respectively.
So here's the suggestion from one of my interviewees who has been active in equal rights campaigning on both sides of the Atlantic:
"In America gay rights are seen as a minority issue for a single interest group," he said. "Equal rights activists could learn from the British example by trying to reach out to their conservative opponents."
Food for thought. Certainly stuff for civil discussion.