Were it not for dramatic political events five years ago Mr James Hamilton would be an unknown civil servant in the Attorney General's office whose legal advice was always cloaked in anonymity.
His existence first became known to the public as "Official B" in the controversy surrounding the delay in the extradition of the paedophile priest, Brendan Smyth, to Northern Ireland. That delay eventually led to the fall of the Fianna Fail-Labour coalition in November 1994, and to the early retirement of Hamilton's superior official in the AG's office.
Names were revealed in the subsequent Dail committee inquiries. Official A was Mr Matt Russell and Official B was Mr James Hamilton. At these hearings Hamilton gave a calm and measured performance, distancing himself from Matt Russell and pointing out that he knew no more about the Smyth case than he had read in the newspapers.
This was not the first time he had had differences with Matt Russell. In the X case he was opposed to the efforts of the Attorney General, Mr Harry Whelehan, under the guidance of Mr Russell, to stop the 14-year-old girl having an abortion in Britain. But his warnings of possibly dire consequences were to no avail.
At the Dail committee hearings on the events in the wake of the Brendan Smyth affair which led to the fall of the government in 1994, Hamilton proved a match for his politician interrogators, telling Mr Des O'Malley: "Obviously that is a matter for you to draw that inference, if you wish. I cannot say one way or another what was on anyone's mind."
This ability to resist pressure from politicians will stand him in good stead in his new job. The first Director of Public Prosecutions, Mr Eamonn Barnes, identified maintaining the independence of the office as the greatest challenge.
"Jim's as tough as nails," said a friend. "No politician is going to push him around and no policeman is going to push him around." He is very highly regarded among his legal colleagues, and no one within a normally bitchy profession could be found to criticise him.
"He is very highly thought of as a lawyer," said a leading solicitor. "He cleared up the mess in the AG's office when he took over in 1995 and built up morale there."
His tenure in that office is widely seen as a success. "He has a very good team there. They do very complicated work and you only hear nice things about them. They work hard for good money, but not that much in comparison with what is to be made by good lawyers in the private sector," said another lawyer.
This sense of public service is another characteristic friends identify in Jim Hamilton, and it was seen in his volunteering for the UN team monitoring the Cambodian elections in 1993. He was the most senior public official to do so.
Later he was part of the EU delegation monitoring the South African elections. He was also involved in the legal side of the drafting of the Belfast Agreement and sees this as one of the high points of his career.
All these roles show an interest in the wider, more political, side of the law, and he is known to be politically astute. As a young barrister he was a member of the Labour Party, but resigned on joining the public service, and has been at pains to keep his political opinions to himself since. Many of his close friends continue to have Labour Party links.
Jim Hamilton was born in Fairview, Dublin, in March 1949, the elder of two brothers. His mother was a teacher in a local Church of Ireland national school. His father, 17 years her senior, was an insurance salesman.
He attended Drumcondra Church of Ireland national school and then the Hibernian Marine school in Clontarf. It had been set up to prepare boys for entry to the British merchant navy and Royal Navy. An uncle was headmaster in the school, which probably explains why he went there rather than to one of the various Protestant secondary schools in Dublin.
He finished his secondary education in the High School, before going to Trinity College to study history and political science.
As well as taking his degree he joined its prestigious debating society, the Historical Society, where he won the Gold Medal for oratory.
He was also active in student politics and took a year out of his studies when elected deputy president of the Union of Students in Ireland. He also edited the student magazine, TCD Miscellany.
He then studied law at King's Inns and was called to the Bar in 1973. He worked on the Northern circuit and from 1977 to 1981 was State prosecutor for Donegal. In that year he joined the Attorney General's office, where his rise has been steady.
His reputation for legal ability, combined with caution, suggests quite a dull figure, but this is far from the truth. Those who know him say he is very sociable and very funny. "He's very good company with a dry, droll sense of humour," said one. "He's great fun, a great story-teller," said another.
A lawyer who was also part of the Irish contingent monitoring the Cambodian elections recalled Jim Hamilton's ability to stay the course with the late-night revellers. "There were hilarious session in the Japanese army camp where we were billeted," he said. "The Japanese were very rigid and wanted lights out at sundown. It didn't suit the Irish delegation at all."
"He loves company, loves going out for a bit of craic, loves sitting around a table with friends and a good bottle of wine," said his wife, Noreen, whom he met in Trinity. She added that he is a wonderful cook.
Unlike many of his colleagues, he will not be found in a golf club or at a rugby match. "He hates ball sports of any sort," she said. "He worked his way out of them at school by showing how good he was at keeping cricket scores."
He does enjoy travelling and has just returned from three weeks touring California in a camper van with his wife and three teenage children, a holiday normally guaranteed to strain all the relationships involved.
As this shows, he is a devoted family man and, according to his wife, enjoys mundane tasks around the house. He loves gardening and "actually likes hanging wallpaper," she said, adding that it gives relief from the stresses of work. The pressures in his new job are likely to lead him to redecorate the whole house.