When two German Christian Democrats, Wolfgang Schaeuble and Karl Lamers, proposed the idea of a core Europe 10 years ago, nobody wanted to listen. Since the collapse of last month's EU summit in Brussels, however, talk of a 'two-speed Europe' is everywhere.
The issue threatens to overshadow today's meeting between the Government and the European Commission, following this weekend's clash between the Taoiseach and Mr Romano Prodi.
Mr Lamers and Mr Schaeuble made the mistake of identifying the hard core of EU member-states that were committed to further integration as Germany, France and the Benelux countries.
Italy, the sixth founding member of the Union, was outraged by its exclusion, and others suspected a Franco-German scheme to pursue integration outside the EU treaties. What doomed the Lamers/Schaeuble plan, however, was the fact that France still believed in its own potential as a global player and showed no interest in creating a core Europe.
EU leaders introduced rules in 1997 to allow member-states to co-operate more closely within the EU system in a procedure known as enhanced co-operation.
The Nice Treaty allows a minimum of eight member-states to pursue enhanced co-operation in any policy area except defence. A decision to allow enhanced co-operation is taken by a qualified majority, except in the case of foreign policy, where the decision must be unanimous.
Despite the introduction of enhanced co-operation, leading French and German politicians have taken a greater interest in the idea of a two-speed Europe in recent years. Germany's foreign minister, Joschka Fischer, called it a "centre of gravity", France's President Jacques Chirac spoke of a "pioneer group" and the former Commission president, Jacques Delors, referred to an "avant garde".
They all agreed that any core Europe must be based on the Franco-German relationship and that it should act as a magnet for like-minded countries.
"Such a group of states would conclude a new European framework treaty, the nucleus of a constitution of the federation.
"On the basis of this treaty, the federation would develop its own institutions, establish a government which within the EU should speak with one voice on behalf of the members of the group on as many issues as possible, a strong parliament and a directly-elected president. "Such a centre of gravity would have to be the avant-garde, the driving force for the completion of political integration and should from the start comprise all the elements of the future federation," Mr Fischer said.
In June 2001, four French Socialists, including the EU Trade Commissioner, Pascal Lamy and the former finance minister, Dominique Strauss-Kahn, published an article in Le Monde calling for a Franco-German federation as a first step towards the creation of a two-speed Europe.
There would be joint meetings of the two parliaments and cabinets and a permanent secretariat to promote economic, cultural, educational, scientific, diplomatic and military co-operation.
The second step would be to appeal to others in the euro-zone who were committed to "a model of social solidarity and external independence" to join the new union. The authors rejected the use of enhanced co-operation within the EU system, which they feared would lead to overlapping core groups.
"We cannot wait for these groupings to aggregate and mesh together in a process too haphazard, long, obscure and complex," they said.
In a joint declaration on the 40th anniversary of the Elysée Treaty last year, the leaders of France and Germany promised to intensify co-operation in a number of policy areas. They agreed to set up a council of ministers with a permanent secretariat and to introduce a common citizenship.
All these initiatives remained within the bounds of activities between states and fell short of a full-scale fusion of institutions. To mark the same anniversary, however, Mr Lamy and the German EU Commissioner Guenther Verheugen proposed a more ambitious union between their two countries.
They called for a congress of members of parliament from each country, weekly meetings of ministers, a permanent secretariat and forums for civil society and the regions. These institutions would agree budget and tax policy, harmonise the tax systems and develop common positions in all international organisations. The commissioners also called for a joint Franco-German army.
The conventional wisdom in Brussels holds that no meaningful EU defence union is possible without Britain, but Mr Lamers, who believes his idea's time has come at last, thinks that Berlin and Paris should ignore London and carry on regardless.
"It is clear that London has no great problem with the present crisis in the EU because London always had a different idea of Europe. They actually joined the EU to prevent the emergence of a political Europe.
"On the other hand, a core Europe will exert a magnetic influence. If the core countries present a united front, London won't want to stay outside forever," he said.