Not the archetypal civil servant is how most people describe Donal MacNally, the new man at the head of the Budget division in the Department of Finance.

Mr MacNally (48), who has taken over from Mr Michael Tutty, is also variously described as extremely hard-working, "a bit of a workhorse" and extremely bright.

An economics graduate of Trinity College, he has a reputation for being completely on top of a brief and is seen as an impressive performer and excellent negotiator. In common with many other senior finance officials, he is not afraid to say no, but those who have had dealings with him say it is never an instinctive reaction but always well thought through. "His looks belie a real toughness," one associate noted.

What marks Mr MacNally out from some his contemporaries in the Department is that he has spent a good deal of his career outside it. He started in the then Department of Industry and Commerce, now Enterprise Trade and Employment, at 17 and stayed there until 1986 when he transferred as a principal officer to Finance.

As he says, this means he has been on the other side of the table trying to argue for funds. "I would not be of the same genre as those people who would see their job as trying to curb enthusiasm." He sees his job as managing a process, making sure policy advice is given and the policy implemented at the end. But he has also spent 15 months looking after the Department of Health's estimate in Finance, a notoriously difficult process given that there is virtually no limit on what could be spent in this area.

He is chairman of the tax strategy group, which makes recommendations to the Government on the Budget. He has been deputy chairman of the group from 1994 to 2000 for all of Mr Ruairi Quinn's budgets and those of the current Minister for Finance, Mr McCreevy. On the morning of our interview, he had been in a meeting of the strategy group but, unsurprisingly, was unwilling to say what had been discussed. "Policy is a matter for the Minister who has to deliver the Budget, not me," he says.

However, he does admit that issues such as the savings bond are on the agenda. Further individualisation of the tax bands is also on the cards but the Minister will not be changing his mind and going further down the road to individualisation of the tax code.

There had been talk that he could jeopardise his prospects by moving to the Department of Finance but, as he says: "Never refuse a promotion." Policy-making is obviously hugely important to him. He points out that Finance is at the centre of things and he always gets a good deal of satisfaction in seeing something carried through.

One piece of legislation of which he is particularly proud is the setting up of the Criminal Assets Bureau, which allows the Garda, the Revenue Commissioners and social services to work together with equal power for the first time. "There is enormous satisfaction in seeing something like that through from beginning to end," he says.

He was also responsible for the Central Bank Act of 1989, which will now have to be revised radically in the light of any legislation on a single regulatory authority. Interestingly, Mr MacNally has a foot in both camps on this issue. He formerly worked in the insurance division of the Department of Industry and Commerce and also in the banking section of Finance, where he was responsible for the flotation of Irish Life.

One of the ways in which he most obviously differs from the more traditional perception of the civil servant is in his lack of aversion to the Freedom of Information Act. One source says also that "he is not afraid to use bad language when the occasion calls for it"; another notes that he does not appear to work on the basis that knowledge is power, meaning that everything must be kept close to the chest. Public discussion and debate is always welcome, Mr MacNally says, and points out that the tax strategy group's papers are released under the Freedom of Information Act almost 95 per cent complete. He adds that proposals to make the Estimates more public are welcome if they mean a public discussion of policy issues, although it may complicate the lives of civil servants.

"Finance is always characterised as preferring to leave things unchanged but that is not a fair representation. We have to point out what the consequences of any action are and things are always connected, but at the same time all proposals for change must be examined on their merits."

A northside Dubliner and native of Blackhorse Avenue close to the Phoenix Park, he always did very well in school. As he says, he was "top of the class" and had a knack of passing exams.

He was less good at sports and despite an uncle and brother who were into football, he never got picked for the team when at St Declan's CBS, Cabra. He has since tried to take up golf but gave it up as a bad job and sticks to bridge, in which he is a keen club player in Glasnevin. The demands of his job mean that he now has less time to travel around the country playing, particularly as many of the tournaments are in the months coming up to the Budget, when, he says, there is not time for a social life. He admits he is very focused and always has been. "I was always interested in getting on and learning things."

When he finds the time, his reading includes biographies and historical novels, which, he believes, one can "learn a lot from". He has just finished the unauthorised biography of Walt Disney, while John Major's and Jeffery Archer's are waiting in the wings. He also has a very dry, some would say black, sense of humour. Someone who has worked with him in the past describes him as "very gregarious" but he is also approachable and speaks his mind. "You can speak your mind to Donal and know that he will reply in the same vein," one person who is close to him noted.

This is the way many of the younger people in the Department, and indeed outside of it, like to do business and as a result his appointment was a popular one.

His staff, in particular, speak warmly of him. He is said to fight for them to the extent possible within the civil service and is always very appreciative of any extra work. When he was moved out of the Budget division last year and was promoted to assistant secretary in the corporate services and public expenditure division, everyone took it as a sign that he would be secretary of a department in the future. With the departure of Mr Tutty to the European Investment Bank, that department is now thought to be Finance, once the new incumbent Mr John Hurley retires.

One of his strong points, according to those who have worked with him, is his efficiency to the extent that if he promises something by Friday, it is usually delivered on a Thursday.

The new job will be a far more public one than he has experienced previously. Many people outside the civil service have had little contact with him. He is not a member of the Foundation for Fiscal Studies or Statistical Society as Mr Tutty was, nor has he been particularly active in the Institute of European Affairs or at the Dublin Economics Workshop in Kenmare - typical meeting grounds between those in the Department and outside of it.

But such gaps in his resume are probably the least of his worries as he now faces into helping to frame perhaps the most important Budget of Mr McCreevy's career. The ultimate test will be December 6th; if he can finish that day and celebrate, it will have been a job well done.