On October 25 2001, in a column entitled “Let the huddled masses go free” (reprinted in my book Against the Flow), I proposed abolishing the tenuous distinction between economic immigrants and asylum seekers and conducting a five-year experiment in which anyone who wished could come and go. Well over five years have passed, and I could no longer repeat the suggestion. Part of the evidence I cited was that the Netherlands, with a higher population density than the UK, had not suffered as a result of a tolerant attitude to immigration and cultural diversity. Now, I could hardly overlook the heightened sectarian tensions in that country following the murder of the film-maker Theo van Gogh in 2004.

Moreover, I cannot ignore the way in which questions of “immigration and race relations” have reached the top of UK voters’ concerns as the most important issue facing the country. The issue has again attracted attention with the report of the House of Lords select committee on economic affairs, which concluded that there was no evidence that net immigration “generates significant economic benefits for the existing UK population”. The reaction to this has been polarised between shocked liberal indignation and tabloids delightedly calling for ever-tougher barriers to keep out newcomers.