Mayor Len Brown can take a bow. Others may have helped turn the Government around on the rail loop - possibly Lester Levy, chairman of Auckland Transport, or Michael Barnett of the Chamber of Commerce, where the decision will be formally announced tomorrow - but the Mayor deserves most of the credit. He made the project his own and promoted it doggedly against those who doubt that rail can be the answer to Auckland's congestion.
The doubters have included every government, National and Labour, of the past 40 years. The historical significance of the decision can hardly be overstated. Many tomorrow will invoke the memory of Sir Dove-Myer Robinson, whose campaign for a railway with an underground city loop started in the 1960s. The project was the central element of Auckland's first urban plan, produced by the Auckland Regional Authority as long ago as 1969.
But this is not the first time the dream has seemed on the verge of success.
In 1973 the Kirk Government agreed to provide electrified tracks and an underground loop - and the ARA, at Robbie's behest, rejected it. Those elements were not sufficient, he said, to produce "rapid rail". Speed was essential to attracting enough patronage to make the scheme affordable for Auckland.
The term "rapid rail" eventually disappeared from plans, replaced by light rail when trams were back in vogue and now by "integrated rail", which means fed by bus services. Whatever it was called, governments remained fearful of the cost and unconvinced that fixed rail routes were suited to Auckland's urban form.
The cost, estimated at $2.8 billion, is a fearsome amount for a short link from Britomart to Mt Eden. Former Transport Minister Steven Joyce argued it would leave little in the kitty for any other projects in the Auckland region over the same period. It is hard to see what has altered that assessment.
While it now endorses the project in principle, the Government has scheduled it for 2020, five years later than the Auckland Council wants, and probably beyond the life of this Government. National may have calculated that since the next government is likely to adopt the scheme, it might as well do so now and collect some credit.
Despite the distant starting date, the decision is a sea-change. It means the debate is no longer whether Auckland should have an underground rail link, but when.
Labour will no doubt go to the next election promising to provide it much sooner than 2020. Mr Brown, having won this battle, can pitch his campaign for a second term on a mission to bring the construction forward.
Aucklanders, meanwhile, should start looking at their financial obligations. National taxpayers might provide half the capital but the operating cost is the element that has most frightened previous governments. Robbie was right, speed is essential to a commuter rail service. Unless it can substantially reduce commuter travelling time it will not lure enough of them out of cars.
The case for the loop conveys the impression that it is the last link in a chain, that once trains can run in a circle rather than terminate at Britomart the full potential of all lines will be unlocked and services will be frequent and reliable at last. Is that credible? Or are there more problems down the line, such as level crossings, isolated stations and the inconvenience of bus transfers?
Suddenly these questions are no longer academic. The Government's u-turn on the loop makes it well nigh inevitable. Whether it is the silver bullet for Auckland or a white elephant, this train is coming.