How to kneecap the recovery

BRITAIN’S economy is back on track, growing faster last year than any other in the G7 group of rich countries. So British firms are expanding—and hiring. But for David Cameron, the welcome boomlet presents an inconvenience. Five years ago, when the economy was in the doldrums, the prime minister made a foolish vow drastically to reduce immigration. The promise always looked unrealistic. Now, as the economy fires up and firms recruit, it threatens to become crippling.