There are different routes to political greatness. Some lead by charisma. Others surf public opinion. David Trimble, the Northern Irish leader who died this week, was neither. He was something rarer: an anti-populist. The Ulsterman, often described as “prickly”, led his people along a hard, unpopular road to a better future. For UK politicians wrestling with the province’s post-Brexit future, he is a model of what fearless honesty can do.

Trimble won a Nobel Peace Prize for his role in the 1998 Good Friday Agreement, the treaty that ended Northern Ireland’s decades-long conflict by building institutions to bind the province’s communities together.

Trimble agreed its terms on behalf of unionism — the community of largely Protestant people who wish to remain part of the UK. Yet when he took the leadership of the Ulster Unionist party in 1995, this seemed unlikely. Never a liberal, he came to prominence supporting the rights of unionist marches to cross Catholic neighbourhoods.

But Trimble could see how a deal with nationalists, the largely Catholic community who wish to unite Northern Ireland with Ireland, could address the central problem. As he put it: “Ulster Unionists, fearful of being isolated on the island, built a solid house, but it was a cold house for Catholics. And northern nationalists, although they had a roof over their heads, seemed to us as if they meant to burn the house down.”

Trimble shared his Nobel Prize with John Hume, the visionary nationalist leader. Hume was a unique political and moral force. But Trimble was a partner who could see opportunities for unionists in peace and lead his community to them. His most important gift was bravery. Unionists were sceptical about engaging with the peace process, which required leaps of faith: could the Provisional IRA really be trusted to disarm? Some wanted to dictate terms to nationalism, as in earlier decades.

Trimble made the jump, and was opposed by hardliners who rejected the process. They offered nothing but accusations of betrayal, but chipped away at his position. Many grand names of unionism today are people who lacked his judgment and foresight — and resigned from his party in protest at what he was building. But Trimble held his nerve even as his party was eroded beneath him. Seamus Mallon, Hume’s deputy, wrote that if his side had “faced the degree of division in their parties that Trimble had, they would not even have been at the negotiating table”.

Even after the agreement was signed in 1998, when Trimble was Northern Ireland’s inaugural First Minister, it took courage to keep going. The Provisional IRA completed decommissioning its arsenal only in September 2005.

This left the easy applause lines to the Democratic Unionist party, which opposed the Good Friday Agreement. The DUP overtook Trimble’s moderate Ulster Unionist party to become the largest party of unionism. The UUP — like Hume’s SDLP — was washed away at the ballot box, but they did something worth celebrating: they ended the campaigns of murder.

There is a lesson here, for Northern Ireland and for the UK’s aspiring prime ministers. Neither senior Tories nor unionist leaders (sadly including, in his later years, Trimble himself) have been blunt with unionists about how the province should work after Brexit; the Good Friday Agreement was designed when the whole island of Ireland was part of the EU.

Repeating what activists want to hear may win votes, but it is a doomed strategy for governing. All of the UK needs politicians willing to recognise the truth, say it aloud and take steps to tackle problems. Such seriousness is at the core of Trimble’s legacy.