IMMIGRATION has undeniably been a good thing for Britain’s economy, according to conventional wisdom. It has brought new talent and dynamism to these shores, and it has helped the economy in other ways. That, up to now, has certainly been my view.

The Treasury says that immigration, by increasing the growth of the labour force, also raises the economy’s long-term or “trend” rate of growth.

The Bank of England, in an assessment of immigration’s impact in its most recent inflation report in August, concluded that the arrival of new workers had the beneficial effect of acting as a job-market safety valve, reducing pay pressures.

One of the recent economic puzzles had been the surprisingly benign behaviour of wages given low unemployment, it said. One reason, reported by its own regional agents, was that employers were increasingly turning to migrant workers to ease labour shortages.

There is certainly plenty of immigration. Official figures released earlier this month showed that a record 582,000 people came to Britain last year, up from 513,000 in 2003.

There were also 359,000 departures last year, slightly down on the 361,000 recorded in 2003. Net migration into Britain was thus 223,000, the highest since the present method of compilation began in 1991, up from 151,000 in 2003.

More Britons leave than return — a record 208,000 departures in 2004 compared with only 88,000 arrivals. In contrast, 342,000 more non-British people arrived than left. Britain has become a magnet for arrivals from the new European Union members in eastern Europe.

Now, however, there is tentative economic evidence that this process may have gone a little too far. The other labour-market puzzle has been in the unemployment statistics. Every month this year the claimant count has risen. The rise is not huge, amounting to just over 60,000 in total, but it is the first such sustained rise in 12 years, and a blot on a successful labour-market record.

At the same time, however, employment continues to grow, by 345,000 over the past year, according to the Labour Force Survey, and by 150,000 workforce jobs, according to employer-based numbers. How can you have simultaneously rising employment and unemployment? John Philpott, chief economist at the Chartered Institute of Personnel and Development (CIPD), has combined the official figures with his own organisation’s surveys and suggests that at least part of the answer lies with immigration.

“Unemployment has risen in the past year not because more people have been joining the count — in fact slightly fewer have done so — but because fewer people are leaving,” he said.

“The reason for this is evident in our own quarterly survey evidence. It shows that when it comes to recruitment, benefit claimants, many of whom are not immediately job ready, are losing out to other jobseekers, in particular growing numbers of immigrant workers.”

The cry, “They’re taking our jobs” has always been the crudest argument used by those opposing immigration. But at present it seems to be true, at least in part. The unemployed, particularly the long-term unemployed, may be less attractive to employers than bright immigrants with a built-in work ethic.

Anybody who questions the beneficial effects of immigration runs the risk of being accused of being further to the right than Genghis Khan. The Tories thought they were striking a popular chord with their election slogan earlier this year: “It’s not racist to want to control immigration.” But the poster slogan, used in areas with high immigrant populations, was regarded by many voters as distasteful and extreme.

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