I'm delighted to be here at Cato, the guardian of true liberalism. Thank you for hosting this event.
And I'm especially honoured to be sharing a platform with one of Britain's most valuable exports, Andrew Sullivan.
On the way over I read Andrew's book 'Virtually Normal'.
He ends by calling for a new politics with a simple principle: that all public discrimination against homosexuals should end, and every right and responsibility enjoyed by heterosexuals should be extended.
But I also read Hearnshaw's 'Conservatism in England', written before my father was born, in 1932.
He concludes: "To conservatives above all others ... falls the task of defending the menaced citadel of civilisation and maintaining the eternal sanctity of the moral law."
Professor Hearnshaw's "misguided revolutionaries" were not gay rights activists, but his clarion call for a faith-based conservatism finds many supporters today.
So can promoting equality for gay people be compatible with conservatism?
In discussing this I'm going to take three things as given. And if they're contentious, they shouldn't be.
First, since - on the most conservative estimates - around 5 per cent of the population are attracted to the same sex, there are more than 3 million gay people in the UK and 15 million in the United States.
People often speak of gays as though we are a society apart from the rest, living in our own quarter.
And a few choose to be apart.
But most of us don't.
We live in every city and town.
We are businessmen and women.
We run shops and stack shelves.
We labour on farms and in factories.
We are fire fighters and police officers.
We save lives in hospitals.
We fight for our countries and sometimes we die for our countries.
Some of us are extraordinary, but mostly we are quietly ordinary.
We are not different. And we don't want to be different.
We're not asking for special treatment.
We are United States or British citizens.
Proud of our countries.
Wanting to play our part in society.
And across the world there are millions of us.
Millions of ordinary people.
Millions of voters.
Second, we can't be uninvented. Being gay is not a lifestyle choice. Our sexuality is a fact. It may be repressed, but it cannot be changed.
Doctors don't try to change a person's colour.
And healers or politicians shouldn't try to change anyone's sexuality.
Whether it is given by god, or set by nature, homosexuality isn't nurtured by doting mothers or weak fathers.
It isn't a condition to be cured and it can't be willed away through prayer.
Third, democracies should subscribe to a fundamental principle: that 'all men are created equal'.
Some claim that the promotion of gay equality has no place in conservatism. In fact, many deny that conservatives should be interested in the equality agenda at all.
It is argued that equality is incompatible with liberty ... that if men are free, they are bound to become unequal.
But conservatives who want people to become better through their own efforts can never stand by while others are denied that chance.
Conservatives should always believe that everyone should have an equal chance in life, regardless of any other factors, and that they should not be discriminated against.
As Robert Levy, the Chairman of this Institute, has recently written:
"Thomas Jefferson set the stage in the Declaration of Independence: '[T]o secure these Rights, Governments are instituted among Men.' The primary purpose of government is to safeguard individual rights and prevent some persons from harming others. Heterosexuals should not be treated preferentially when the state carries out that role. And no one is harmed by the union of two consenting gay people."
Today I want to explain why I believe that conservatism is not only entirely compatible with the principle of equality between gay and straight people ...
... but that such equality is in fact an essential element of modern conservatism.
I want to explain how David Cameron has re-shaped the Conservative Party in the UK.
How we have developed a progressive conservative agenda, to secure important social objectives through conservative means.
How we have made a commitment to the vital institution of marriage a central part of our programme.
And how we believe that this institution is strengthened, not weakened, by extending its ambit to same sex relationships.
I am not here to preach or to interfere in your affairs.
I am here neither to tea party nor to go clubbing.
But I can tell you what happens to a party when it closes the door to sections of our society and is reduced to its core vote. It's no fun being in opposition for thirteen years.
And I can tell you what happens when a Party opens its doors again and broadens its appeal.
A successful political party should be open to all and ought to look something like the country it seeks to govern.
In recent history the Conservative Party in Parliament reflected only a section of our society - male, white, professional, grey-suited and straight.
At the last election, of our 193 MPs elected, just 17 were women, only two black or minority ethnic and two were openly gay.
If we were truly representative of the country we would have 99 women, 16 black or minority ethnic and 10 gay MPs.
So our party leadership recognised the need to change.
Change because we are a national party which needs to be able to speak to, and speak up for, all sections of society in all parts of the country.
As David Cameron said on Monday, "Unless you can represent everyone in our country you cannot be a one nation party."
Change because we need to reconnect politics with a public who are increasingly disillusioned with a political class.
And change because it was the right thing to do - to promote an environment where people can succeed and live without fear, regardless of their gender, colour or sexuality.
We now have more female candidates, more black and minority ethnic candidates and more gay candidates.
In fact, if we secure a majority in the House of Commons of just one seat, we are likely to have more openly gay MPs on our benches than the Labour Party.
The Conservative Party leadership was not alone in recognising the need to change.
Gay candidates have been selected by local party members - not imposed by the leadership.
I - an openly gay man - was selected before the last election by my local party, voted for by grassroots conservatives, and I've been promoted on merit.
I'm one of two Conservative MPs who have taken out a civil partnership - thanks to legislation which - to their credit - the current Labour Government introduced, but which the Conservative Party supported.
I led our Party's support for a new law to prevent the incitement of hatred against gay people - subject to our concern that temperate comment should not be criminalised.
And our Party Leader, David Cameron, has publicly apologised for Section 28 ...
... legislation introduced by a previous Conservative Government which effectively prohibited the teaching of the validity of gay relationships in schools ...
... a law which was deeply unpopular not just amongst gay people, but with those who saw it as a divisive and unpleasant sign of state intolerance.
We needed to say sorry for a stance that was wrong.
And we showed that as a Party we were willing to admit mistakes and set a new course.
The importance of marriage
In his first speech to the Conservative Conference as Leader of the Party - a major event which brings together party activists from across the country - David Cameron said something extraordinary.
Defying the critics who claimed that party leaders could no longer express a moral preference for the institution, he spoke of the importance of commitment and marriage as the bedrock of our society.
But then he added: "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."
And when he said these words, the delegates applauded. Not a half-hearted ripple of applause, but a spontaneous burst of approbation.
At that moment, we knew that the Conservative Party and British politics had changed.
David Cameron has put marriage at the centre of our prospectus for the next election, arguing that society is broken, and that we need to recognise the importance of marriage in providing a stable environment in which to raise children.
But in supporting marriage he has not done so in such a way as to denigrate or even exclude gay people.
In fact, the opposite, because we have recognised that commitment and stability are important in all relationships.
I appreciate the view held by some, on a strict reading of their faith, that marriage is a unique arrangement which is only available to a man and a woman.
And we should never dictate to religious organisations who are doing no harm that they should, in their own rites or places of worship, depart from their sincerely-held beliefs.
But in the UK, we created in law a civil union for heterosexual couples, specifically devoid of any religious ceremony and significance for those who do not wish to marry in church.
So what religious grounds could there be for opposing the extension of a secular institution to gay couples through the introduction of civil partnerships in 2005?
And why stand against the extension of a civil institution which demands a public declaration of commitment and stability?
Those who argue against legal recognition for gay partnerships often claim that many gay people have promiscuous lifestyles.
But there are few social incentives of the kind which conservatives should naturally embrace for gay people to embrace commitment.
There's little social support ...
... no institutions to encourage fidelity or monogamy ...
... and precious little religious or moral outreach to guide gay people into what may be seen as more virtuous living.
So it's right to recognise commitment in gay partnerships.
In the same way, we should reject discrimination against gay couples who wish to adopt.
I believe that the best parental arrangements are represented by a good father and a good mother, and children should never be treated as some kind of high value consumer good.
But this ideal of a loving and present father and mother is often not realised. So we should not seek to prevent adoption by same-sex couples who may offer a love and stability that is absent from too many homes.
We should not say that, whatever their talents, despite the contribution they can make, there are things that people may not do simply because of their sexuality.
In the UK we've allowed gays to serve openly in the military for ten years.
To bar people from making the most profound commitment to their nation, or to ask them to live their lives dishonestly by not telling, is something no conservative should support.
As Israel - hardly a country which goes in for soft defence - has understood, and in the words of Barry Goldwater, "you don't have to be straight to be in the military; you just have to be able to shoot straight".
I don't believe that conservatism should be a closed membership club.
We must be open to everyone because we believe that everyone should have a chance.
Conservatism at its most powerful has always been a uniting creed.
We're conservative because we believe in strong defence and the nation state.
We're conservative because we believe in responsibility and justice.
We're conservative because we want to strengthen society and limit government.
We're conservative because we're sceptical about big government and have faith in our institutions and families.
Since Disraeli spoke of 'one nation' we have always understood the importance of maintaining a strong society.
And we have never confused that goal with faith in big government or state action.
The progressive conservatism which David Cameron has espoused is in the true one-nation tradition.
It's about using radical conservative philosophy, politics, and policy to serve truly progressive goals.
It's about fostering local democracy, engagement and accountability by returning power to town halls, neighbourhoods, and individuals.
It's about pursuing a family agenda that lets parents take responsibility for their children's education, allowing them to set up their own schools so that we can give everyone a fair chance in life.
It's about developing bold approaches to tackling poverty and inequality in all its forms, engaging more actively with the voluntary sector and encouraging a revolution in social responsibility.
And it's about recognising that there is such a thing as society, it's just not the same as the state.
If we stand against equality of opportunity, which should be an article of faith for the Right, it becomes the preserve of the Left ...
Warped into an agenda of state interference, targets and central control ...
... when it should be about getting out of people's way and letting them advance.
Consensus on gay issues
In the UK, all three major political parties are now assuring gay people that it's safe to vote for them.
Typically, far from taking pleasure in this new consensus, the Left has greeted it with dismay.
For over a decade they have sought to build a client state, where groups are beholden to their generosity.
And now they want to open up 'clear pink water' between themselves and the Conservative Party.
There's an election coming, and it suits our opponents to argue that we haven't changed.
But we self-evidently have changed. I suppose, in a small way, my presence here is evidence of that.
The truth is that there are millions of people who we drove away but who share our values and want to join us.
Gay people are not the property of the Left, or of any party.
They are not an interest group or a political commodity to be traded.
They are not vessels for votes.
Gay people are motivated by the same issues as any other voter.
They will vote for the political party which best sits with their views - so long as that party does not make itself taboo.
Moving the agenda forward
For the modern Conservative Party, embracing gay equality is neither a temporary phenomenon, nor an agenda which can be reversed.
We know that we have further to go to modernise our Party
If we form the next government, we intend to entrench the progress made on gay equality, and to move the agenda forward.
If there is a need for new laws, we will consider them.
But we will also understand where we should give a lead, and where there is a need for law.
Conservatives should never leap to legislate.
So we will show leadership in demanding action to tackle homophobic abuse in sport, where behaviour and role models can exert such a powerful influence on young people ...
... as we should demand action against all abusive behaviour on the playing fields.
We will take the strongest stand against the homophobic bullying of children in schools ...
... as we should take a stand against all bullying - and we will not allow our support for faith schools to undermine that stand.
We will insist on action against hate crime where gay people are the victims ...
... as we should insist on action against all hate crime which incites fear and violence.
We will speak out when countries abuse the human rights of gay people ...
... as we should speak out when any human rights are abused.
None of these areas necessarily require new laws.
But they do require a clear-sighted and determined conviction about the importance of political leadership in promoting human dignity and equality.
When I was born in 1963, homosexual conduct was a crime.
I, and millions of others, are free to be who we are now because of the courage of political leaders who saw that this prohibition was wrong.
I, and thousands of others, are free to enter into a civil partnership now because of the courage of politicians who saw that to exclude us from making that commitment was wrong.
And the need for this leadership has not gone away.
So let us be clear about the kind of society we want to build.
One where a child can go to school without being bullied because of his or her sexuality.
Where people can be honest with their friends and families and employers, and not live a lie.
Where the terraces at football games do not ring with homophobic abuse.
Where a public declaration of lifelong commitment to another person can be made by anyone.
Where communities are safe and no-one is fearful because of who they are.
Where anyone can serve their country without being asked who it is they love.
Where no-one is held back and opportunity is available to all.
And where the Prime Minister of the UK or the President of the United States could just as easily be gay as black.