Since the euro arrived, 'the pound has enjoyed its longest period of stability in recent times', insisted Lewis, of Monument Derivatives. He said sterling, adjusted to reflect Britain's trading relationships, has moved in a 3% band on either side of 107 since 1999. 'The euro, in contrast, has moved over a 20% range.' The average year-on-year change is 2.7% for the pound, 5.1% for the euro.