Belfast Agreement @25: Without David Trimble's courage and brains, Northern Ireland would have ended up with joint authority - Ruth Dudley Edwards

For the last few weeks I've been listening, watching, reading and thinking a lot about the 1990s, the period when I began my journalistic career.

Every day on Twitter I read entries about people murdered during the Troubles — frequently by their neighbours — and every day I rage about the futility and cruelty of that squalid sectarian war and the terrible suffering it brought to hundreds of thousands.

My memory is full of great friends I made at that time who resisted bigotry and terrorism and have since died, like Chief Superintendent Roy Cairns and those fine Orangemen the Reverend Brian Kennaway, Michael Phelan and Ian Wilson. All of them maintained their Christian principles despite the constant demonization of their institutions.

I’m haunted at the moment by memories and images of two close friends, David Trimble and Lyra McKee, both featuring heavily in the news. In a strange way these two good and gifted but very different people almost bookend my personal experience of that period. Both were enemies of sectarianism, as had been my southern Irish parents.

I was fortunate to have inherited from my historian (half-English) father a straightforward belief that the history of Ireland was the history of all the people of Ireland. And from my mother - the daughter of a gamekeeper on an Anglo-Irish estate in Cork who had fought in the First World War - a contempt for those whose ethnic rage drove them to murder their neighbours. I also had my paternal grandmother upstairs who was fixated on the men of 1916 and the importance of dying for Ireland so I knew what to avoid. My parents — both great readers with a deep distrust of ideology of any kind — thought she was nuts. And in very sectarian Dublin, it mattered to me that my parents — and my big brother — had Protestant friends. I occasionally went across the border to a history conference, but I knew few who lived there.

I left Dublin in 1965, became a London civil servant and from 1969 became increasingly aware of and appalled by what was happening in Northern Ireland. Being from a southern, Catholic, nationalist background, I had found it easy to get to know nationalists, and as an ex British civil servant, I was also on easy terms with British diplomats, many of whom I got to know at Anglo-Irish conferences I was invited to after becoming a freelance writer in 1979. Meeting some Ulster Protestant academics and politicians, I was coming to enjoy bluntness, brutal honesty, straight answers and the absence of grievance-mongering.

But suspicious unionists were hard to get to know. David Trimble and I, however, had interesting chats over the years after we met in 1985. When his election as UUP leader was announced at an Anglo-Irish conference, I was the only person who spoke up for him. The British and Irish establishments, unlike me, hadn’t bothered to get to know him. The Provos were furious when Trimble was elected for they recognised that he was smart. They set about his destruction from the first day with their brilliantly orchestrated lies. There was fury when my reports from within Orange ranks described how parade clashes were being cynically orchestrated by the IRA. In August 1997, I remember standing in the Bogside with Mitchel McLaughlin as he explained to me smugly that Trimble was already finished.

And of course they demonised anyone who supported him. I was surprised at how quickly I became an enemy of Ireland in the eyes of Irish diplomats and newspaper readers who could not grasp why I thought it reasonable to try to explain the point of view of unionism to Irish audiences. David and I learned to trust each other and despite many misgivings, I supported the Belfast/Good Friday Agreement.

I have an instinctive loathing of the IRA which I regard as a cancer on the island and I believe the British and Irish governments mishandled the negotiations that the republican leadership cynically exploited for purely party reasons, but I have no doubt that without the agreement there would have been many many more murders and broken hearts. And I have little doubt that without the courage and brains of David Trimble, Northern Ireland would have ended up with a horrendous dogs’ dinner of joint authority and possibly civil war.

John Hume, with whom I had been friendly, denounced me as an enemy because I criticised him. David, however, laughed when I said in an article that photographs of him and Ian Paisley holding hands in Portadown made them look like the principals at a gay wedding. It was no accident that many of David’s closest allies during the agreement negotiations (people like Eoghan Harris, Sean O’Callaghan and me) were originally from the nationalist tribe but came to respect this honourable, truthful, open-minded man who was prepared to argue out differences of opinion and sought no flattery. David needed all the help he could get, for nationalism had the support of the EU, the Irish Department of Foreign Affairs, and to a considerable extent the Foreign Office, while he, deserted by absolutists, was fighting the unionist case almost alone. The odds against him were atrocious, but his moral and physical courage were inspirational. Today I'm trying to focus on all the lives saved by the agreement but it’s hard to shake off the personal sadness.

I mind very much that with the exception of Bertie Ahern, with whom David developed a important friendship, while he was alive there were few people in Ireland or the US that recognised that without him there would have been no agreement. Since his death, he has been receiving much more of the respect and love he deserved. So has Lyra, but it's heart breaking to think of that gallant, brilliant, loving little creature being snuffed out in the name of a fight for Ireland freedom that only morons still support. But thank you David and Lyra. You fought as best you could for decency and your communities. I am proud I was your friend. Now I hope the good people North and South will focus on making this honourable agreement work.

• Ruth Dudley Edwards is author of The Faithful Tribe: an intimate portrait of the loyal institutions