It was a long time coming, but yesterday's call by dissident unionist Jeffrey Donaldson for unity within the Ulster Unionist Party may yet prove to be one of the defining moments in the struggle for unionist hearts and minds before Friday's referendum vote.

He may still be saying No to the agreement, but the Lagan Valley MP took the first step towards melting the ice between himself and his party leader with his impassioned plea for unity within the UUP after the referendum, no matter what the result.

The obvious inference is that while the Bright Young Man of unionism may not like the agreement, he is prepared to do his bit to make it work.

Consequently, his opposition to the deal has been diluted. The Yes campaigners have won an important battle, if not yet the war.

Just how important that battle has become is highlighted by almost every opinion poll conducted in recent days. An abnormally high number of unionists - perhaps as many as 35 per cent - are still unsure to how to vote, though most say they will.

They have read the text and listened to all the arguments, but still they are unsure, circling the agreement like big cats around a porcupine, knowing that underneath the spikes there is something worth digesting, but fearing personal damage in the process.

The people with the furrowed brows in the polling stations will all be unionists, wondering until the very last minute where to place their crosses.

Their wariness has been nurtured during a decade in which the Anglo-Irish Agreement, the Downing Street Declaration and the Framework Documents have contrived to create a culture of suspicion which has had the effect of convincing unionists that no good can come from any document which bears the joint imprint of the British and Irish governments.

No one knows for sure how the don't-knows will vote on Friday, but they alone retain the capacity to help deliver the magical 70 per cent endorsement the governments seek, or to reject the agreement, drag the Yes vote under the 60 per cent mark, and produce a result that would be celebrated only by Ian Paisley and Bob McCartney's anti-agreement united unionists.

What is certain is that unionists will vote in unprecedented numbers on Friday, raising the possibility of one of the largest turnouts for a United Kingdom election. In one section of the unionist community, the Protestant middle classes, people who have not bothered to go anywhere near a polling booth for 20 years or more, will be standing in line. They will be saying Yes.

The signing of the agreement, and David Trimble's prominent role in forging an accommodation between the two traditions, sparked a significant surge of renewed interest among that section of unionists for whom politics had become a dirty word.

In the days before the district councils became a sectarian battleground many of them put themselves forward for election to their local authorities, seeing it as their responsibility to put something back into the communities they lived and worked in by way of public service.

Others had no difficulty with wearing their political hearts on their sleeves. Unionism was something to be proud of.

THAT all changed when the Troubles started and politics became a nastier and sometimes sordid business, in which unionists from one camp slugged it out across the debating chambers with those of another - and then Sinn Fein arrived to turn up the temperature even further.

The vast majority of middle-class unionists simply didn't want anything to do with it.

The signing of the agreement has brought nothing short of a transformation in middle-class attitudes towards what would naturally be the party of their choice.

And the new, upbeat mood could signal a more dynamic future for the Ulster Unionist Party if its current divisions are healed.

Above all, there is a sense of excitement about David Trimble as a unionist leader. There is respect and admiration for what he has done. Trimble has reopened the door to those who wouldn't become involved in the party because of what they perceived as its Stone Age ideology. Now they see a leader who has negotiated well, who has won the respect of the British Prime Minister and the British people, and who is not afraid to take risks for peace and stability.

For those who realise there will never be a return to the days of a Protestant parliament for a Protestant people, the agreement holds out the first real hope of a Northern Ireland in which people can sort out their own problems and work together to build a better society.

Had Northern Ireland not suffered 30 years of civil unrest and terrorism it would have changed dramatically, even under a Stormont administration.

With the Catholic population growing, the nationalist influence on Stormont would by now have made its presence felt. In reality, today's Stormont might not have been so different from the assembly envisaged in the agreement. That is recognised by those who have mortgages, homes, businesses, children at university, a stake in society, and that includes many who are members of the Orange Order.

According to the Spirit of the Union group, which has been taking out newspaper advertising to spread the message that even Orangemen are free to say Yes, the agreement has many positive aspects for unionism.

The group claims to speak for a large body of Orangemen, and one of its principals is David McNarry, who walks with the Ballynafeigh LOL, the lodge involved in the bitter Ormeau Road dispute.

For years he has been influential in trying to defuse the tensions surrounding the annual walks which would take the Ballynafeigh brethren from their district hall and over the Ormeau Bridge, past the hostile nationalist enclaves, to their church services at St Anne's Cathedral or to meet other lodges for the Twelfth of July parades or Apprentice Boys marches.

A senior Orangeman in the area said: "Short of talking to the residents' group, David has done everything he can to overcome the obstacles to peaceful and dignified parades along the Ormeau Road. None of us can talk to the residents because we believe they are being mischievously driven by Sinn Fein/IRA. But if there was a genuine intent on the part of ordinary residents to reach an accommodation, David would be the man to walk into the lion's den."

His influence has grown in the Orange Order since marching disputes became a compelling issue following the IRA's 1994 ceasefire, and some see him as the future grand master of an institution which becomes as firmly focused on the 1990s as the 1690s.

But he has another reason for supporting the agreement. Like many members of the order he is a small businessman with a modest stake in what a prominent Ulster businessman, Sir George Quigley, describes as "Northern Ireland plc".

The problem with a No vote is that it will destabilise investment and see a return to uncertainty, he says. In a nutshell, it will knock the confidence of people who are waiting to bring jobs and money into Northern Ireland. It isn't difficult to imagine how pessimistically the big boys like Sainsburys, who have brought huge investment and hundreds of jobs to the province, will react to an emphatic No response.

WHAT is not generally known is that the Orange Order also has a stake in Northern Ireland plc. Contrary to their public image, members throughout the country's towns and villages aspire to be pillars of society. The order pumps large amounts of money into its own charities, some of which provide bursaries for disadvantaged young members to encourage them towards higher education and keep them off the streets.

It pays for tools, equipment and courses to help young people take apprenticeships, but it cannot of itself provide the jobs. What we should be doing is creating an environment in which training flourishes and there is a steady demand in the employment market for young people with skills.

For that to work, Northern Ireland still requires a river of investment.

The negative impact of a No vote won't encourage outsiders to speculate here, said one member.

The order also has a number of credit unions, keeping worse-off brethren and their families away from the urban loan sharks who prey on the unemployed and penalise them with high interest rates. Then there is the Property Development Company, an unlisted company on the secured share market, which was ostensibly created to provide financial help for members forced by the IRA from their homes and land in Border areas.

Like any other credit unions and financial institutions, their viability would be affected by the nervousness which would inevitably accompany a No response.

The upshot is that as an institution considering its response to the Good Friday agreement, the Orange Order has found itself in a position not unlike that of many Protestants in the North. It has grave misgivings over issues such as the release of prisoners, the credibility of the decommissioning arrangements and the spectre of Sinn Fein leaders sitting in government while the IRA remains armed and intact.

But its members live in the real world, and the viability of Northern Ireland as an economic unit impacts on all their lives in a way that is perhaps more fundamental than the right to walk along any street of their choosing at any given time.

If come Friday there is still uncertainty among a large section of the unionist population, it is because people are trying to weigh up the obvious benefits that would materialise from a long period of stability and a vibrant Northern Ireland economy, against the gut instinct that tells them that what the agreement amounts to is rather more than a tampering with the edges of their society.

If they can live with that, and concentrate on what Jeffrey Donaldson described as the many pluses in the deal, the vote in the North may not be too far short of the magical 70 per cent the Yes campaigners want.

Geoff Martin is editor of the News Letter