Tony Blair should hold his nerve. Far from regarding EU enlargement on 1 May as a threat - because it will allow unrestricted access to migrants from the new member states - the UK should see it as an opportunity.
A million eastern European citizens already live within the EU. More than two-thirds reside in Germany and Austria, the countries that share the strongest geographical, economic and cultural links with eastern Europe. It is estimated that fewer than 50,000 are living in the UK and, of those, only 40 per cent or so are here to work, many of them in high-skilled employment. The rest are students, spouses and children.
The latest EU research suggests that this situation is unlikely to change after 1 May. Most migrants from the east will stay close to home rather than come to the UK; only some of those who do come will seek employment; and many of those will be highly educated.
Postponing free movement for up to seven years as permitted under EU rules - a provision that Blair's critics are pressing him to use - is likely to have a marginal impact on long-term flows. Projections suggest that flows might peak in the first few years after the new members join but that they will then reduce gradually as those countries catch up economically with the rest of the EU. The number of migrants is expected to peak at roughly four million around 2030, but even then, less than 5 per cent (about 160,000 people) are likely to be living in the UK (see table).
At the low-skill, low-wage end of the labour market, the relatively small influx of migrants is unlikely to have a significant impact on wages or employment levels. But as these will be legal migrants, it will offer an opportunity at least partially to regularise the present black market in labour, which has led to people working in the sort of conditions that led to the Morecambe Bay tragedy.
The UK and Ireland are alone among EU states in proposing to allow citizens of the new members unrestricted access to labour markets. But here lies the biggest opportunity of all. The question, after all, is not whether the migrants come, but when. Free access now will attract the best and brightest of them. And this is the best possible time for them to come, with the economy robust, with unemployment at its lowest rate for two decades, and with a desperate need for healthcare, engineering and other skills in some regions and some public services - skills possessed in abundance in eastern Europe.
In seven years' time, when the gates will have to be opened anyway, things may not be so rosy. Indeed, we increase the chances of their not being rosy if we miss this opportunity to fill shortages, thereby boosting the economy and helping towards better delivery of public services.
Dhananjayan Sriskandarajah is Research fellow at the Institute for Public Policy Research