Estimating the overall effect of this influx of enthusiastic low-cost labor is hard, although a recent study by Ernst & Young, an accountancy fine, suggested that without it Britain's GDP would be 0.2% lower. In fact, nobody knows how many workers from what were once called captive nations are actually in Britain. The government's official (but voluntary) worker registration scheme records 345,000 since Britain opened its labor market to such workers in 2004.
But, notes Dhananjayan Sriskandarajah of the Institute for Public Policy Research, a think tank, this disguises "huge chum". Workers may register and then leave the country. Others may not register at all. It costs pounds 70, and the advantages it offers, such as the right to claim the dole in future, may seem flimsy. It is the prospect of work, not state benefits, that attracts east Europeans to Britain.
Four other west European countries Spain, Portugal, Finland and Greece opened their labor markets on May 1st to workers from the new Europe, while France promises partial liberalization and Holland is thinking about it. But that will do little to dent Britain's lead. A widely-spoken language and thriving networks incorporating previous immigrants still make Britain a prime destination, with Ireland close behind.
Does continuing the hit00-or-miss registration scheme make sense？ The government considered scrapping it altogether on May 1st, but decided not to. One reason is that some existing formalities could come in handy if, as seems likely, the EU expands on January 1st 2007 to include Romania and Bulgaria. It has not yet been decided whether workers from these two countries, which will be the poorest in the EU, should be given free access to Britain's job market. Mr. Sriskandarajah's institute reckons that, if allowed, 41,000 workers are likely to come from Romania and 15,000 from Bulgaria. The government could scrap the registration scheme for Poles and the like, while keeping it for the newcomers.
The registration scheme may produce misleading figures, and it is a curious use of official time and energy at a moment when bureaucrats are too busy to deport foreign rapists. But it is a sop to public opinion, which is twitchy about Britain's increasingly open borders.
We learn from the beginning of the passage that ______.

A. punting is rarely seen along the waterways of oxford and Cambridge nowadays
B. most of the employees in the punting-rentals firm are from Eastern Europe
C. most of the veterans are the local people who can speak English as a guider to the tourists
D. the punt chauffeurs can earn 14 pounds a day