This is, said Mr Ruairi Quinn yesterday, the achievement of "a lifetime's political ambition . . . a dream come true". Mr Quinn has indeed had a lifetime of political ambition. Through the years since his early political activism in the 1960s, he has made clear his view that politicians need to be in power to achieve what they want to do and that he enjoys power.
Now he leads the party he joined 33 years ago, his Dail seat as safe as a house, an impressive ministerial career behind him; and, at 51, he can reasonably expect to have his greatest political achievements in front of him.
However, before he gets his hands on the power he needs to make advances, he must first revive the Labour Party's depressed morale, define what it stands for and lead it back to electoral success.
Mr Quinn did not come to Labour through a traditional trade union route. His political consciousness was formed during student protests in UCD in the late 1960s, an exciting, heady and sociable form of political expression which still allowed you time to get your degree. He was no dilletante, however, and was always serious about politics.
His image was, and remains, more colourful than that of the average party activist. As a young Ranelagh-born architect in the 1970s and early 1980s, he drove a trendy black Volkswagen Beetle and handed out fresh red roses to his canvassers on polling day at a time when such a symbol was seen as namby-pamby by starry plough, pin-wearing Labour types.
He has always had a penchant for the flamboyant gesture and image: the light-coloured suit in the Dail chamber's sea of grey, navy and black; the loud tie; the fat cigar; the campaign car blasting Manfred Mann's The Mighty Quinn at election time.
He comes from a Ranelaghborn, Sandymount-bred family of achievers. One brother, Lochlann, is a successful businessman and chairman of AIB. Another, Conor, is managing director of the QMP advertising agency. Another brother, Declan, is professor of medicine at the University of Saskatchewan, Canada, while another, Colm, is a doctor. His cousin, Feargal, is a senator and owner of Superquinn.
At Blackrock College, Ruairi won a Leinster Senior Cup medal as a wing-forward on the rugby team. He also won a national championship at middle-distance running and a place on the national student athletics team.
He joined the Labour Party branch at UCD in 1964. It was an exciting time to be involved in student politics - the 60-member branch sometimes attracted up to 400 students to public meetings. He later became involved in broader student activism as revolutionary fervour swept the then Earlsfort Terrace campus on issues ranging from demands for greater student involvement in the running of the college to opposition to the Vietnam war.
Mr Quinn was regarded as a moderate by many of those belonging to more exotic strands of the left within the broad Students For Democratic Action (SDA) grouping which came into being in 1968. Even then he was seen as a man who wanted to win and exercise power rather than simply make fiery speeches.
His activism spread outside UCD into the housing action committees and he campaigned for the opening of Merrion Square to the public. "It seemed to everyone that he would end up in politics," says one fellow student activist from that time.
On his return from post-graduate study in Athens, he began working as an architect and, at the same time, began building up the depleted party organisation in Dublin South East and his own position within it. The depletion was due to the fact that many in Dr Noel Browne's 1969 organisation had been expelled from the party or had resigned after the party's bitter coalition conference.
His chance of advancement came quickly. When the selection convention for the 1973 general election took place, Dr Browne stood down and Mr Quinn took the nomination. In the subsequent general election, he was just 39 votes short of a Dail seat, despite a collapse in Labour's vote from 24 per cent to 11 per cent.
He held the nomination despite opposition from a lively left within the constituency which eventually dissipated. Mr Quinn's election to Dublin Corporation in 1974, and nomination to the Seanad in 1976, gave him the base from which he won the seat in 1977 by 250 votes.
He lost the seat briefly in 1981 and scraped back on the 11th count in February 1982. He has held it at every election since, each time making it safer. His constituency machine is among the busiest and most professional in the State.
In November 1982, the new Tanaiste and Labour leader, Mr Dick Spring, picked Mr Quinn to be his junior minister in the Department of the Environment. As an architect, Mr Quinn had written considerably on the social problems of urban growth in Ireland. Environment suited his interests and he quickly impressed with ideas on conservation, local government renewal, planning control and inner city renewal.
However, when Frank Cluskey resigned from Cabinet in late 1983 and Mr Spring decided to move to another department, it was to Labour, and not Environment, that Mr Quinn was appointed as a Minister. Despite his disappointment at not getting Environment, Mr Quinn threw himself into his relatively low-profile post, inaugurating go-ahead projects such as the enterprise allowance, TEAMWORK and the Social Employment Scheme.
He attracted criticism from those in Labour who were sceptical about Labour's participation in government at the time. He was seen as too comfortable in power; they felt he should be seen to stand up to Fine Gael more in defence of pet Labour projects, such as the National Development Corporation, company law reform and the broadcasting Bill.
Mr Quinn calls himself a socialist and agrees to being a pragmatist. The only reservation Labour Party members have about him is, as one put it yesterday, "his socialism has never been known to win out over his pragmatism".
He often mixes socialism with pragmatism in the same speech. In 1977, he informed a Rotary meeting in Dublin that Labour's aim was to transform Irish society into a "socialist workers' republic". However, he went on to say more wealth would have to be created first, and that the public and private sectors should both do more to create jobs.
In coalition with Fianna Fail from 1992, he was the Labour TD given the most senior economic brief, Enterprise and Employment. But this turned out to be only a warm-up for his appointment as Minister for Finance in the Rainbow Government.
Labour's achievement during Mr Quinn's time in Finance was to show that it could handle the government's most senior ministries. With Mr Quinn this came as no surprise: his pragmatism and commitment to being in government ensured there was no major loosening of the purse strings and no run on the pound. As chairman of the European Council of Economic Ministers, ECOFIN, during Ireland's EU Presidency, he steered through crucial agreements to lay the foundations for the single currency.
Yesterday, after his election, he was back on a familiar theme. "The Labour Party has become a party of government," he said. "The party wants to get back into government." This, he explained, was not for the sake of prestige, but so it could transform the country in the way it wanted to see the country transformed.
At 51, he has time to have a good go at it.