The rises come at time when many Londoners face a pay freeze and the retail price index is running at -1.4%, and on top of a 6% increase in fares this year.

U.S. stocks retreated after six straight gains for the Standard &Poor’s 500 Index, amid declines in consumer shares after a government report showed retail sales fell in June.

Meanwhile, us retail giant Walmart has launched a "sustainability index", which by 2013 should give details of the total environmental costs associated with various products.