IT was a unique opportunity and I felt that if I turned it down I would spend the rest of my life regretting it." That is how David Begg, former general secretary of the Communication Workers' Union, explains his decision to become chief executive of Concern, the international aid agency - a position he takes up tomorrow.

By coincidence, his former colleagues will be gathering in Belfast for the biennial conference of the Irish Congress of Trade Unions. Many of them are still coming to terms with the notion of someone resigning as general secretary of a trade union to do something else. In the old days trade union leaders were usually carried out of office in a coffin and they have only recently reluctantly come to terms with the notion of retirement and a life after the union. At 47, David Begg is a mere whippersnapper.

But he has never been a traditionalist in his approach to life, although some of his values are very traditional indeed. He has a deep and abiding religious faith, and would describe himself as both a liberal and a Catholic.

He brings a strong sense of vocation to everything he does. When he switched from being an ordinary employee of the ESB to deputy general secretary of the ESB Officials' Association in 1978, he says it represented "a quantum change in terms of level of responsibility". He adds: "My wife regards the time before that as a sort of nirvana, when I used to come home every evening at a quarter to five."

In 1985 be became general secretary of the Postal and Telecommunications Workers' Union. By 1989 the PTWU had amalgamated with the Communications Union of Ireland to form the CWU. In large part it was due to David Begg's strategic planning, something which has marked him out as one of the trade union leaders of his generation.

His strategic management skills are the most obvious quality he brings to his new job, but it isn't the only one. Although he doesn't engage in the heavy socialising or intensive backslapping some trade union leaders feet necessary to keep in touch with the membership, he elicits a fierce loyalty from postal and telecommunications workers.

This is partly due to his ability to deliver. But be also has a rare capacity to communicate his own ideas and commitment to the troops. He can become uncharacteristically emotional when be talks about the members.

OR instance, three weeks in to the bitter 1992 dispute at An Post over the use of casual labour, he recalls visiting the old Sheriff Street sorting office in Dublin. He had just concluded a long meeting with the then minister, Brian Cowen, which failed to resolve the strike. "I went down to meet the officers of four or five branches and report back. They were waiting at the gate and you could see the tiredness and strain in their faces."

To his surprise there were another 800 workers inside the building. "They had been waiting for hours. The sheer emotion of that sort of situation is hard to convey; the idea of leading people in a quite desperate situation.

I had to deliver a moraleboosting speech, provide some sort of hope and reassurance we were doing what was right". He says the meeting was the high point of his career as a trade union leader, although the strike dragged on for another four weeks. "People won't understand that," he says, "but I've always felt a heavy responsibility in situations where people give you an immense degree of trust".

He finds leaving the CWU quite hard. "People have been very good to me, given me fantastic loyalty. Members can be very hard to deal with at times but they take you in like a family. I think, if it was any other job except Concern, I would have found it impossible to go.

"But the type of work Concern does, and the scale of need in developing countries is so great, there is no comparison to what you can achieve here. So from that point of view it was a very easy choice to make."

Having served formerly on the executive board of Trocaire, David Begg comes to Concern with a good working knowledge of how international aid operates, although he is a little uneasy about his lack of experience as a development worker on the ground. Asked why he can't leave the task to others, he replies: "If you live in the third of the world that is affluent and people in the other two thirds are on bare subsistence, it is very difficult morally to be comfortable with yourself.

"I think a tot of people just don't appreciate the scale of poverty that does exist. But if you do know, you cannot easily walk away from it.

"The job seems to match some of the goats I have. At the end of my life I would like to be able to say I did make a difference in other people's lives. That can be true of, work in the trade union movement too, but not on the same scale."

"The Garret FitzGerald column in Saturday's editions was a reprint of an earlier column due to an error in the handling of a computer disk. The error is regretted.