Stevenage has a Labour MP for the first time since 2010, as part of what looks set to be a national landslide for the party.
Kevin Bonavia won 17,698 votes, and will now sit in the House of Commons as Stevenage's representative.
Conservative Alex Clarkson finished second with 11,080 votes, while Reform UK's Peter Hopper finished a strong third with 7,667 votes.
They were followed by Lisa Nash for the Liberal Democrats (3,467), Paul Dawson for the Greens (2,655), and Joshua Smith for the Christian Peoples Alliance (148).
It is the first time a Labour MP has been elected in Stevenage since 2005, when Barbara Follett won for the third time.
Every election since, from 2010 onwards, had been won by Conservative Stephen McPartland, who chose not to stand again this time.
In his victory speech, Mr Bonavia said it was the "honour of [his] life" to be elected as Stevenage's MP, and promised to "return the role of MP to its founding purpose - service".
Turnout was lower than at any other general election in Stevenage since the constituency was created in 1983, at just 60.4 per cent.
It meant that Mr Bonavia's winning number of votes was around 8,000 lower than the total won by Stephen McPartland for the Conservatives in 2019.
Reaction to come.
Kevin Bonavia's victory speech in full
"It is the honour of my life to have been elected as the Labour MP for Stevenage, Knebworth, Codicote, Datchworth and Aston.
"In our town and our villages, we ran a campaign of hope. We sent a clear message that regardless of who you supported in the past, choose Labour this time, and we'll deliver the change that you need.
"Residents here answered that call, and for that I am forever grateful.
"I'd like to thank the returning officer, the police and the count staff for ensuring a safe, efficient and professional count this evening.
"As always, you have ensured our great democratic process can flourish.
"I'd like to thank my opponents too.
"It has been, at times, a tough and relentless campaign but I know that each of you had the best of intentions for our constituency, and that is the best of our British democracy.
"I'd like to thank my team, my family and my friends, many of whom are here tonight, for their undying passion, dedication and relentless hard work across the years as we've worked on this project to deliver a fresh start for Stevenage.
"In the last six weeks alone, through the long days on the campaign trail, your enthusiasm and drive for change has kept me going every single day.
"The Stevenage Labour family is a big one, so I'm afraid I can't name you all tonight.
"But there are a few I do want to single out. Of course, my brilliant agent, Tom Plater, who kept everything secure and safe on our campaign.
"And my phenomenal campaign manager, Guy Lucas-Bhana, who ensured that my focus was always, always speaking with the people I hope to represent.
"And finally, Laura Ven, for being a brilliant office manager. Thank you all, and thank you all of you who have helped deliver this result tonight.
"Most importantly, I'd like to thank my constituents. Whether you voted for me, or you voted for someone else, or you didn't vote at all, in me you will always have an MP who is local, accessible and on your side.
"Public service is in my DNA. My mum and dad instilled in me from a young age that if someone needs help, or there's a problem that needs to be fixed, you roll up your sleeves and you fix it.
"That's the kind of MP I will be. It's no less than you deserve after 14 years of failure.
"This is my home, and it's yours too. Together, we are going to change things for the better, and slowly, things will get better, as the signs now point not just to a change of MP but to a change of government that will transform our country, including the many residents I've spoken to in this long campaign.
"And so, to Lee, who had to sell up because his mortgage payments skyrocketed after the economic crash - Labour will restore economic security so that never happens to another family again.
"To Esther, who stays under blankets because she can't afford to turn the heating on before midday, Labour will launch GB Energy to drive down your bills and guarantee energy security in an increasingly volatile world.
"And to Alistair, who is stuck on a waiting list backlog for an operation, Labour will deliver 40,000 new appointments per week to get you the treatment that you need.
"Now, I won't read the whole manifesto, but I hope that gives you just a flavour of the change we strive to deliver, and locally, my focus is clear.
"I'll open an accessible constituency office, deliver surgeries across our town and villages, visit every school, shop and business in my first term, and represent you with pride and purpose in our parliament.
"In doing this, I will return the role of MP to its founding purpose - service.
"Service to you, your family, our town and our villages.
"Tonight, I am humbled by this honour, and this awesome responsibility that you have placed upon me.
"So as I finish these words, my service now begins. Thank you."
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