The first part of Mr Wardle's argument rests on the view that Europe has become an economic magnet for migrants. This is true: after a long period when Europe was a source of emigration, it became the target of immigration again in the latter 1980s. This was largely because of its increased prosperity, but also a result of political changes. The main sources of this movement over the past 10 years have been the countries of central and eastern Europe, after the collapse of the Berlin Wall; the Maghreb and the Middle East; and parts of Africa.
In the 1990s, the immigration pressures on Europe have been focused overwhelmingly on one country - Germany. It is the point of arrival for many people from central and eastern Europe as well as for those who fled the war in former Yugoslavia. In 1992 alone, 123,000 asylum seekers arrived in Germany from former Yugoslavia, 104,000 from Romania and 231,000 ethnic Germans arrived from eastern Europe.
The rate of migration into Britain remained fairly steady during the 1980s, at around 60,000 to 70,000 a year - compared with the 1970s and early 1980s, when around the same number were leaving Britain every year. It is perfectly possible to argue that the only thing stopping a much larger wave of immigration has been the valiant passport officer.
The second element of Mr Wardle's argument is that Brussels wants Britain to drop passport controls. This is also correct (see box, below right). But his third contention - that once controls are gone, Euro-welfare scroungers will be taking all the best seats on the Eurostar - is a bit more dodgy. There is little evidence of a vast mass of people desperate to claim lavish British welfare benefits if only they could slip into the country. Britain cannot stop EU citizens from coming in and claiming welfare benefits if they meet the conditions - but they do not seem to want to come in large numbers. About half of Britain's 2 million population of foreign status are from Europe, but two-thirds of those of those are from Ireland, with which Britain has ties centuries old. And the rights of open access to benefits do not necessarily extend to those from third (non-EU) countries who are resident in Europe.
Britain's welfare benefits are not especially lavish by European standards, certainly compared to those of Germany, Denmark, the Netherlands and Sweden. These countries are also richer than Britain. None, bar Germany, has experienced a flood of newcomers, though all have experienced a rise in immigration - legal and illegal - and have tightened their controls as a result, even without having passport controls on their national borders.
It is possible, of course, that migrant communities could decide, once they had arrived in Europe, to head for Britain in search of work, perhaps attracted by Britain's lax regulations on employment. In general, however, migrants tend to remain in areas where they have family and where their communities are already established. The main source of legal immigration is the arrival of family members. The possibility of - for instance - a rapid movement of immigrants from the Maghreb through France to Britain seems very unlikely.
Finally, Mr Wardle argues that the EU is encouraging an immigration free- for-all. This is very misleading. The European Union has spent the past five years accumulating measures that make it more and more difficult for immigrants and asylum seekers to get into Europe. Only last week a group of EU countries got together to reintroduce visas for people from former Yugoslavia and impose stricter identity controls.
Once central Europe joins the EU, its citizens would be free to enter other states, of course. If London believes that these people would come straight to Britain, it is free to oppose their countries' membership. But the whole point of membership is to stabilise their economies and bring them up to Western norms, making emigration a less attractive option. Ireland, for instance, has already seen emigration stabilise and fall while in the EU. It is called economic integration, and even Tory Eurosceptics say that free trade is what the whole exercise is supposed to be about.
The approach taken by Europe on the movement of people has been consistent from the start: remove internal borders while toughening up controls on the exterior. Immigration policy is made between EU governments, and member governments retain national vetoes on virtually every related aspect. Germany is pressing for European moves to complement its own in reducing the influx of asylum seekers; France's interior minister, Charles Pasqua, has made his name with tough moves to clamp down on immigration, prompted by fears of Algerian civil war. While men like him are running Europe's interior ministries, the chances of national capitals losing their grip on policy, or of sudden outbursts of liberalism, seem remote. Mr Wardle is tilting at windmills.