They are the Democratic Unionist Party founded by the Rev Ian Richard Kyle Paisley, later Baron Bannside.
He was the hardline Protestant Unionist opposed to any settlement of the Irish “Troubles” that involved compromise with the Catholics. He opposed all attempts to resolve the conflict through power-sharing between unionists and Irish nationalists/republicans, and all attempts to involve the Republic of Ireland in Northern affairs. Think Sinn Fein’s Gerry Adams.
This guy was his equivalent on the other side. His party has historical ties to banned paramilitary loyalist groups, including the Ulster Defence Association (UDA) and the Ulster Volunteer Force (UVF).
DUP is a group of people not born to compromise, anti-abortion, anti-gay marriage, anti-climate change. They are not going to be a voice for progress or reason in the British Parliament. But they will wield extraordinary power.
The new force in British politics DUP leader Arlene Foster
Sinn Fein leader Gerry Adams warned that “history will show that alliances between Ulster unionism and British unionism have always ended in tears. That’s always been the story.”