The conference, expected to last more than a year, is intended to improve the efficiency of EU institutions and pave the way for the accession of as many as 12 new members in the next century. Unless Britain, France, Germany and the other member states overcome their disagreements, there is a risk that the EU will postpone the admission of leading contenders such as the Czech Republic, Hungary and Poland.
To judge from the Government's White Paper issued last Tuesday, Britain's position on the IGC differs from those of France and Germany in two fundamental respects. First, the British message is unashamedly anti-integrationist, opposed to any steps that could dilute national sovereignty in favour of pan-European institutions.
Second, Britain has no intention of following France and Germany into an "inner circle" of EU states which want to press ahead with closer integration and insist that no country should have the right to block them. This applies above all to the creation of a single currency and the political institutions needed to accompany it.
Britain will not necessarily oppose the emergence of an inner circle, which the French Prime Minister, Alain Juppe, defined on Wednesday as "a small number of states around France and Germany". However, like Spain, Denmark and other potential outsiders, Britain is anxious that the inner circle should not set rules that turn it into an exclusive club.
On some points, Britain and France seem closer to each other than to Germany. Both believe the EU's centre of gravity should rest with the Council of Ministers, representing national governments, and national parliaments rather than with the European Commission or the European Parliament.
The British and French are blocking a proposal to let Euro-MPs attend the IGC as negotiators or observers, a stance that parliamentarians in Strasbourg say reinforces the EU's image as a remote and undemocratic organisation. For its part, Germany believes it is important to enhance the parliament's powers and reduce the "democratic deficit" in the EU because otherwise it will prove difficult to sustain public support for closer integration.
Although the defence of the nation-state may seem to represent important common ground between London and Paris, France is clearly closer to Germany on the need for monetary union. The French regard this as so crucial that they will almost certainly have to make concessions to Germany on pan-European political integration.
Strictly speaking, monetary union is not up for discussion at the IGC because the matter is viewed as having been settled at Maastricht in 1991. How-ever, the issue is sure to hang over all the IGC debates as long as doubts remain over whether the project can start on time in January 1999 and which countries might make the grade.
Britain is at odds with its main partners over extending the system of qualified majority voting in the EU decision-making process. Significantly, however, the White Paper signals that there may be room for a compromise, as it accepts that enlarging the EU to the east - which Britain regards as a vital objective - will require changes in the majority-voting system.
Germany and France are less addicted to majority voting than is sometimes understood in Britain. Thus France opposes majority voting on foreign policy and immigration matters and Germany, sensitive about deploying its soldiers abroad, opposes introducing the system in defence policy.
Britain does not share the French and German enthusiasm for running a common defence policy under EU auspices, and can probably count on the support of neutral members such as Sweden and Finland. Moreover, Britain's military weight may make it impractical for the EU to move to a joint defence without British participation.
Overall, however, it is the Government's unalloyed resistance to closer integration that makes Britain the odd man out in Europe. Some EU diplomats say there is a serious danger that deadlock will set in at the IGC and the conference may need to be suspended until after the next British election, when the new government should feel able to take a more flexible negotiating position.