Predictably, her harshest warnings were reserved for those seeking to establish a European defence identity; for her, the creation of such a structure can only supplant the United States and lead to disaster. Yet, even on this subject, she is out of tune with current reality: the British Government's White Paper on Europe, scheduled to be published this week, will outline a stance towards European defence that is not very different from the former prime minister's vision. More importantly, the Labour Party has few differences with the Government on this score, and Britain is actually winning the defence argument in Europe.
For much of this decade Europe has been paralysed by an arid dispute chiefly between three countries. France argued that the continent must start providing for its own security to compensate for the inevitable withdrawal of the American military commitment. The British retorted that such measures could unravel the North Atlantic Treaty Organisation. And the Germans claimed that it was possible to square the circle by having both a strong European defence and a strong Nato with the Americans at the same time.
The outcome of this fight was the 1991 Maastricht arrangement, which pledged EU members to a "common defence policy, which might in time lead to common defence". But at the same time, and largely at Britain's insistence, foreign and security policies were left outside the EU centralising activities; the Western European Union (WEU), an organisation which pre-dates and remains separate from the EU, was tasked with co-ordinating the continent's military activities.
It is true that some, particularly the Germans, have pushed over the past few years for the creation of a European defence identity, complete with a central political command in Brussels. Much more will be heard of such proposals when the EU's Intergovernmental Conference begins in Italy later on this month.
But the experience of Yugoslavia and the sheer bureaucratic complexity of a European defence identity will mean that the result will ultimately be nothing more than an informal and ad hoc military arrangement between France, Germany and Britain (the serious military players on the continent) and the US which simply cannot be decoupled from Europe.
Those still pushing for an eventual European army like to claim that, as the debacle in Yugoslavia indicates, Europe will never be taken seriously unless it has the necessary military forces in order to impose its will.
Few arguments could be more misconceived. A European military structure, if it is to be taken seriously, will require a massive investment in airlift and naval capacities, satellites and intelligence-gathering facilities. Far from increasing their defence expenditure, all European countries are reducing their budgets and the Germans have done most of the cutting.
Europe failed in Yugoslavia not because the EU was divided but precisely because the continent tried to speak with one voice and ended up with irrelevant policies. For the first six months of the Balkans war the EU tried to keep the country together without having the slightest idea how this could be done. The Balkans disaster is therefore a warning of just how flawed security policies run by consensus can be.
The idea that Europe must have the capability to act on its own is based on the assumption that the continent will be subjected to crises where the Europeans feel threatened but the Americans will somehow have no interest. But nobody has identified a realistic scenario where this would apply.
Russia, the Middle East, North Africa and the Baltic states are all potential flashpoints, yet in all of them the US has at least as big a strategic stake as the Europeans. The European efforts in Yugoslavia collapsed because Europe failed to co-ordinate its actions at every step with Washington; a superpower such as the US simply cannot be absent from handling such a conflict.
Despite the cacophony of various proposals and the diplomatic noise which now surrounds the question of Europe's defence identity, a consensus is being created - and one which any British government could accept. The WEU cannot be incorporated into the European Union because the membership of the two institutions does not overlap: the EU has neutral countries which are incompatible with a military alliance.
The French have understood that there is no substitute for American military might, and President Chirac has practically abandoned the Gaullist policy of keeping a distance from Nato. Furthermore, everyone accepts that a senior figure should be appointed to represent the EU in future crises; as long as this person co-ordinates policies rather than negotiates security deals, even Britain should be happy.
But, most importantly, Britain cannot be outvoted on security issues. While in monetary affairs it is possible to envisage a scheme from which Britain is absent, no coherent military structure is feasible without the British armed forces, which are some of the most substantial on the continent.
In short, Europe's future security arrangement will be a compromise which maintains the freedom of states to act on their own, but also allows for joint action. The ultimate lesson of Yugoslavia is that if France, Britain, Germany and the US agree on a course of action, nearly everything is possible; if one of these states seriously disagrees, almost nothing can be done. No amount of bureaucratic "construction" from Brussels is likely to change this equation, if only because in defence matters military hardware speaks louder than any vision.
The debate about Europe's defences is now almost entirely fuelled by the extremes, people like Baroness Thatcher and Chancellor Kohl, two personalities who curiously complement each other. Kohl genuinely seems to believe that unless Europe ultimately has a single army and government, his Germans - whom the Chancellor still regards as partly a nation and partly a disease - will be tempted to dominate Europe. And Lady Thatcher assumes that without the Americans, the Europeans will not be able to run their own bath.
The reality remains, however, that a common European security identity is a question of degrees. None other than Britain will need the EU in the years to come in order to put pressure on the Chinese to respect the treaty for Hong Kong's handover. And the US is one of the states most keen on the Europeans assuming a greater burden for their own defence.
The lady who only six years ago was calculating, King Canute-style, how to prevent Germany's unification has no vision to offer for Europe's future. And the Chancellor who achieved Germany's unification is equally out of step. A European defence identity is being created, but it will be one flexible enough to accommodate the varieties of the continent, and one doomed to include the Americans for many years to come.
The author is Director of Studies at the Royal United Services Institute in London.