Inflation was persistently high throughout 2010, with an average RPI of 4.6% - the highest since 1991. Meanwhile, the CPI has been above 3% for the last 15 months, a whole percentage point above the Bank of England’s 2% target, prompting Mervyn King, the governor of the Bank of England, to write a total of four letters to George Osborne, the Chancellor of the Exchequer, explaining the causes for such consistently high inflation.