The dollar, the Swiss franc and the Japanese yen all fell by 1.7% against sterling, making them the joint weakest performers among the major currencies. For the franc and the yen, the decline was a function of waning appetite for their safe-haven qualities. The catalyst for the dollar's retreat was last Friday's US employment report. Including revisions to previous months, the number of people on nonfarm payrolls was 130k fewer than investors had expected; quite a big miss. 

Sterling, meanwhile, was going gangbusters. It was the top performer among the major currencies, strengthening by an average of 1.1% and adding two and a third US cents. The UK economic data were no great shakes, especially the numbers for manufacturing and industrial production. However, an analyst at one of the big banks helpfully pointed out that the pound had strengthened against the US dollar every April for the last 14 years.