Seven generations of Kerrs have farmed in Fermanagh. Tonight the old man will cast his vote for traditional Unionism. But his son has other ideas. By David McKittrick

"Aye," said a man who knows Bertie Kerr. "He'd be a good Unionist to talk to, you'll meet no more decent man in a long day's walk. He'd be typical enough. His son isn't afraid to speak up either." And so it proved.

The Kerrs are a pleasant family who live in a lovely place, a spotlessly tidy farmhouse with a commanding view over a beautiful part of Fermanagh, Northern Ireland's lakeland. Eighty miles from Belfast, 14 from the border, this a place of unspoilt rolling green countryside, of loughs and trout lakes. But a nearby, slightly dilapidated Orange hall, Union Jack fluttering outside, serves as a reminder that it is also a land of perpetually unfinished political business.

Bertie Kerr is one of up to 860 grassroots delegates who will tonight file into Belfast's Ulster Hall to choose the next leader of the Ulster Unionists, Northern Ireland's largest political party. Their decision may well be a defining moment, indicating whether Unionism is to participate in the peace process or remain on the sceptical sidelines.

The Kerrs are a most welcoming family. Mrs Kerr settled us in the living room, providing tea, scones, butter and jam. Bertie arrived from the farm in his working clothes, having tended to his beef cattle and pedigree Charolais. His son, David, appeared in jeans and check shirt, a tall intense young man, and he and father sat on either side of the Aga.

Bertie is friendly but has no airs and graces: indeed, like many Protestants this is a matter of some pride with him. He referred to it as soon as he was asked what sort of direction the party should take. "In my opinion it's very simple," he began in his mellifluous Fermanagh accent. "We've been our straight, honest, blunt selves for the last 25 years and we've took a hell of a battering and we've stayed together and we still have our pride and we still have our authority and our majority. And I think it's a bad time to be changing tack, quite honestly."

Bertie Kerr is a councillor and a member of the party executive, but on Friday night he and the rest of the 860 will all be equal, the party hierarchy and the grassroots casting just one vote each. Some of the 860 have a close involvement in politics but others have only an occasional interest, which makes voting patterns difficult to predict.

London leader-writers may be urging the delegates to branch out and opt for radical new directions, but the heart of the party consists of men and women like Bertie: wary, conservative people who show few signs of aching for intoxicating new departures. The slate of five MPs - Ken Maginnis, William Ross, the Rev Martin Smyth, John Taylor and David Trimble - spans a spectrum from the immovable to those who might be innovators, but is heavily loaded towards the former. Bertie reflects the party's inclination towards caution.

He goes on: "We've held it together and we've kept it together. Having held the fort for 25 years, and after 25 years of burying our dead, I certainly don't want to do anything very sudden or very outrageous to the Unionist party at the present time.

"We have to be damn careful and we have to play our cards very close to our chest. We're very much on our own: we've Irish-Americans against us, the SDLP, Irish republicans, the southern government, the British government - and they all have the one aim, and that's to get over this Unionist problem. We stand very much on our own, and we need a man that's not easy pulled about."

As he spoke, his son sat listening intently, sipping his tea. David, who is 21, has just started work as a trainee solicitor in Enniskillen after three years studying law in Manchester. He would like to get into Unionist politics but, unlike his father, he thinks the time has come for innovation.

"I got my eyes opened when I went to England," he says. "I got away from the Fermanagh Protestant environment, away from the flag-waving and all. And you go away and you're in an impartial environment, mixing with people of all different cultures, and you look back and you say: 'What the hell's wrong with us, where are we going wrong?'

"Everybody across the water just sees it as an Orange and Green issue, but it doesn't have to be that way. It can be argued out in real terms, and that's the way I want to see our politics go. It's because of the sectarianism, because of the propaganda and the rhetoric and the grip the churches and the politicians have over the people. I'd like to sweep all that aside."

David Kerr argues for a new Unionism which would go beyond the Protestant community - all 860 people in the Ulster Hall tonight can be expected to be Protestants - and look attractive both to Catholics and people in Britain.

"I believe now we have a new opportunity," he says. "We're entering a new era. If we can hold on to the ceasefire and stabilise the country I think Unionism can change and can become a broader political ideal. It can become more acceptable to more people. I keep coming back to this when I'm talking to Da about how Unionism should go forward. I believe we should be trying to sell it politically, economically, socially and culturally. We have to focus on increasing our electorate and marginalising militancy. We need a leader who can do that - a leader who is good with the media, who is good with convincing both Unionists and nationalists and people across the water."

The Bertie Kerr listening to his son's youthful idealism has been fashioned by centuries of history. At least seven generations have lived in frontier Fermanagh, around Derrygonnelly, Garrison and Ballinamallard, for 250 years. He served six years in the RAF; six or seven in the B Specials, seven years in the Ulster Defence Regiment.

More than 30 of his friends and security force colleagues have been killed by the IRA. One night in the Seventies he didn't go out with his usual UDR patrol because he was tired. The patrol stopped to check out a parked car less than a mile from the Kerr farmhouse: it blew up, killing Alfie Johnston and Bertie's best mate, Jimmy Eames.

Bertie says the IRA tried to kill him at least once, but adds that he has a lot of Catholic friends. "That may have kept me reasonably safe because I wouldn't have been a popular man to kill," he says with a smile. But, as a councillor, would Catholics vote for him?

"Well, they've not yet come round to voting for a Unionist councillor, except for a handful of people, but they have this thing that if you don't push them into a corner they'll not lift their coat and go out and vote against you; they don't go out at all. In some Orange circles and right- wing Unionist circles they give the Catholic community no credit at all, but I know very well that there are good, decent people in the Catholic tradition in Fermanagh."

So what about his son's proposition that they might be brought to support the Unionist party? "Now, they're not going to fall over themselves to vote Unionist. In one way David's absolutely correct; but the thing that worries me is that if you change tack and open your party up to this, that and the other you can lose some of your traditional support."

David interrupts him to say with some animation that the party need not change anything substantial about Unionism and did not have to lose its traditional support. "All I'm saying is that we have to shake off this sectarian sort of cloak, this Orange cloak that smothers Unionism. It's been strangling it for far too long, and its going to sink the ship."

"Your traditional support is not going to be easily brought with you," his father replies. "You know it's going to take a bit of time to convince those people. We're at such a critical stage of negotiation, and there's so many pressures on us, that we're not in a position to take severe risks. If we could get an agreement that would be a different matter, but at the moment I wouldn't be for taking risks."

David says: "The party needs young blood. I've been at Unionist meetings with Da, and I've seen graphically how backward their thought processes are. I think there's a real lack of vision there; I think they're still living in the past."

"I know Irish republicans seem to be having more success than us," says Bertie, "but, it would be a very poor, very bad move on behalf of the Unionist party to start changing now. Maybe the new man would be more amenable to the media than James Molyneaux was, but he was a good leader. I'd like to see a man who would lead the party on much a similar line."

David says: "I don't believe you should be reliant on a head-count of Orangemen, on a head-count of Protestants, and just say: 'Well, we have those people, those people are going to vote for us, Unionism is secure as long as we have those numbers.' We have to build trust between the people, and I believe one of the ways forward is through integrated education."

Bertie shakes his head. "I wouldn't agree with that, now." But he concedes: "OK, we do need changes, but we need a bit of progress and a bit of power before we start to implement them." Electing the new leader, he says, is the most important thing he will do this year, because the party is the main bulwark for their British citizenship and their Protestant Unionist culture against Irish republicanism.

And then his deepest fear comes to the surface. "If we get taken over and the Irish mafia get their way, they'd be putting the foot down very hard on our culture and everything to do with us, and we haven't any place to go." At that point it becomes clear that tonight's election goes far, far beyond mere politics.

In the view of Bertie and most of those who will be marking their ballot papers, this is not just about winning or losing elections. It is about culture, heritage, a question of survival. To the outsider those green Fermanagh hills are beautiful: to Bertie they are something which must be guarded with eternal vigilance against that feared Irish foot.