So the US Federal Reserve cut by 75 basis points rather than 100 basis points: when the numbers are big enough, a small difference between them can seem unimportant. But with rates down to 2.25 per cent, every 25bp makes a significant difference to the Fed's brave but perilous monetary policy.

There was ample bad news for the Fed to ponder, from evidence that the real economy is now finding it harder to borrow money, to accelerating falls in house prices; from consistently weak job creation to the near failure of Bear Stearns. The Fed's focus on reducing the danger of severe recession calls for looser policy than current inflation would normally justify, and if the Fed wants rates below 2 per cent, it is right to move there quickly.