HOPES of lower British interest rates received a boost from figures for the price of goods leaving the factory gate. Output prices fell in July by 0.1 per cent, the first time such prices have fallen for three months in a row. In June they dropped 0.2 per cent, and there was a 0.1 per cent reduction in May. Last month's fall slowed the annual pace of price increases to 2.2 per cent from 2.5 per cent in June. Last week the Bank of England called for a pre emptive rise in interest rates to keep the British government's inflation target on course.