London bus passes Swiss Re Gherkin building Reuters photoLondon, once one of the world’s most expensive cities, now ranks in the middle of the pack of European cities in terms of the cost of living. The sharp drop in the value of British pound largely is to blame for the decline of London’s ranking from the second priciest city three years ago to No. 22, according to a study of comparative purchasing power by UBS of 73 cities around the globe.