By Jon Kelly
Political reporter, BBC News
The first Gay Pride marches were a response to the Stonewall Riot in June 1969
New York's Stonewall riot in 1969 is credited with launching the gay rights movement - and 40 years on, its impact is still being felt by politicians in the UK.
It seems a world away from modern-day Westminster, where openly gay MPs and peers sit around the cabinet and shadow cabinet tables while politicians on all sides of the House profess their tolerance.
On 28 June 1969, following a campaign of police harassment, patrons of Greenwich Village's Stonewall Inn - mostly gay men, lesbians and transvestites - fought back following a raid.
The event prompted the first gay pride marches, inspired a new wave of the equality movement and eventually gave its name to the campaign group Stonewall.
The impact of this movement can be witnessed during the past dozen years when the age of consent was equalised, civil partnerships were permitted and the ban on gays in the military was overturned.
And another legacy has been to allow gay and lesbian politicians into the mainstream - not just demanding equal rights, but as representatives of the wider community.
MP David Borrow recalls reading about the riots in 1969, the same year that he became involved with politics by joining the Labour party - and concluded he would not be able to make any progress within its ranks.
Sexual relations between men had been decriminalised in England and Wales just two years previously, gay and bisexual politicians - like Labour MP Tom Driberg and Tory peer Lord Boothby - stayed firmly inside the closet for the sake of their careers.
"Coming to terms with my own sexuality involved deciding not to pursue a political career - the idea of someone who was gay being an MP seemed very strange," Mr Borrow remembers.
But this was to change. After he began serving as a councillor in Preston from 1987 and as MP for South Ribble a decade later, he says he was "not out in a conventional sense" - his sexuality was not a closely-guarded secret, but nor was it much of an issue to his constituents.
In 1998, after consulting with his partner, he made the decision to "clear the air" and come out publicly so he could talk frankly about the bill to equalise the age of consent.
The reaction, he says, in his "middle England, fairly Catholic, marginal constituency", was relaxed.
"By the mid-1990s, the public was ahead of the House of Commons," he adds.
Path to office
And indeed, at the time of Mr Borrow's declaration, gay politics and gay people in politics were already becoming familiar and respectable.
Chris Smith - who in 1984 became the first MP to come out by telling an audience: "I'm Chris Smith, I'm the Labour MP for Islington South and Finsbury and I'm gay" - had been elevated to the cabinet.
The campaign group Stonewall UK, named after the riot, had been formed in 1989 by household names like Sir Ian McKellen and EastEnders actor Michael Cashman, and its then director Angela Mason quickly became well known. Its moderate tone may have attracted criticism from more radical veterans of the gay rights movement, but lent its advocates greater media respectability and a hearing from government ministers.
So for a next-generation politician like shadow environment secretary Nick Herbert - at 46, a decade younger than Mr Borrow - the path to office appeared clearer.
Mr Herbert insists he has never experienced discrimination in his political career. When he sought the Conservative nomination for the safe Tory seat of Arundel and South Downs, he brought his partner Jason Eades to the selection meeting - and was chosen as the candidate without any fuss.
"In a true-blue area, that happening is a sign of things changing," Mr Herbert insists. "I don't think it would have happened 10 years ago.
"There's been a fairly rapid change in attitudes over the past decade - some of the legislative changes have had something to do with that. But in other ways politics has been behind the rest of the public."
Derek Munn of Stonewall agrees. He traces the upswing of the gay rights movement to the battle against Section 28 - the clause of the 1988 Local Government Act forbidding the teaching of homosexual relations as "a pretended family relationship" - which led to his organisation's formation and brought the campaign into the mainstream.
According to Mr Munn, the forthcoming Equality Bill will offer more or less equal treatment before the law, but social issues like homophobic bullying will remain as pertinent as ever.
With the government's own estimates suggesting around 6% of the population is gay, he says, there should be 39 gay, lesbian or bisexual MPs.
Yet Stonewall says instead just 11 are out - only one of whom, Angela Eagle, is a woman.
"There is still work to be done, and much of it is about increased visibility," he says.
Although they span the political divide, both Mr Borrow and Mr Herbert agree that equality will truly have arrived when they are no longer seen as gay MPs, but as MPs who simply happen to be gay.
"When no-one writes another article about gay people in politics, then we'll know we've got somewhere," Mr Herbert says.