LONDON, ENGLAND - MAY 23:  Workmen fly the American and British national flags on the Mall ahead of the visit by US President Barack Obama on May 23, 2011 in London, England. Mr Obama is conducting a week-long tour of Europe with First Lady Michelle Obama. The couple will visit Ireland, the United Kingdom, Poland and France; where he will attend a meeting of the G8 counties.  (Photo by Oli Scarff/Getty Images)