There are moments that make you really proud to be an MP. Tonight was one of those as the Commons gave the Marriage (Same Sex Couples) Bill its third reading.

But what I feel most of all is proud to be a Labour MP. I feel tonight like I did when I walked through the aye lobby in 2000 for Labour’s bill to equalise the age of consent; to repeal homophobic section 28 in 2003; to vote for Labour’s civil partnerships bill in 2005; to ensure that there can be no discrimination on the grounds of sexual orientation in the provision of goods and services in 2007 and to pass Labour’s Equality Act in 2010. Tonight’s vote was another step in a long journey and I feel privileged to have been a part of it.

I’m proud of the leadership shown by Labour to rescue the Marriage (Same Sex Couples) Bill in the last two days from the mess that was caused by David Cameron’s inability to persuade large sections of his own Party to back it. He claims that this is a key piece of legislation for his ‘modernised’ Tory party, but two of his own Cabinet Ministers and eight junior Ministers disagreed with him. Scores of his backbenchers defied him and he has only succeeded in getting this reform past its Commons stages with Labour votes. He claimed the amendments on civil partnerships for heterosexuals would wreck the bill, but really he was just scared of his mutinous backbenchers. It was a good job Labour was there to pick up the pieces. He is a floundering Prime Minister who can’t even persuade his own Party to back him on a flagship bill.

I’m proud to be Labour because equality runs through the heart of my Party. We’ve always fought discrimination, even when it wasn’t easy or popular. We’ll lead the fight to get the bill through the Lords, and we’ll keep leading the charge for LGBT rights.

When I came out in September 1998 I was the first openly gay woman in Parliament and the first lesbian in a ministerial post. I was prepared to lose my seat if that was the price of being open but I needn’t have worried. I got nothing but support from John Prescott, my Secretary of State at the time, Tony Blair, the Prime Minister, and even more importantly my wonderful, understanding and supportive constituents in Wallasey.

I have always believed in the power of politics to change the world for the better which is why I joined the Labour Party when I was just a teenager. It is days like today that I feel my faith in politics is justified and I hope that in this age of cynicism people will see the potential for positive progress in political involvement.

I want to say to LGBT teenagers watching this bill progress: I know there is still more to do before our fight for equality is won. I know that some of you are still bullied and intimidated and feel isolated and alone. I know that we still have work to do to prevent homophobic attacks and ensure that all LGBT people can expect to live in our society free from fear. But we are getting there and tonight’s vote was one more step along the way.